diff --git a/mongoose.c b/mongoose.c
index 9602e79494..742551b870 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -4511,9 +4511,20 @@ void mg_tcpip_arp_request(struct mg_tcpip_if *ifp, uint32_t ip, uint8_t *mac) {
 
 static void onstatechange(struct mg_tcpip_if *ifp) {
   if (ifp->state == MG_TCPIP_STATE_READY) {
+    struct mg_connection *c;
     MG_INFO(("READY, IP: %M", mg_print_ip4, &ifp->ip));
     MG_INFO(("       GW: %M", mg_print_ip4, &ifp->gw));
     MG_INFO(("      MAC: %M", mg_print_mac, &ifp->mac));
+    for (c = ifp->mgr->conns; c != NULL; c = c->next) {
+      if (ifp->is_ip_changed) {
+        if (c->is_listening || c->is_udp) {
+          c->loc.ip4 = c->mgr->ifp->ip;
+        } else {
+          c->is_closing = 1;
+        }
+      }
+    }
+    ifp->is_ip_changed = false;
   } else if (ifp->state == MG_TCPIP_STATE_IP) {
     mg_tcpip_arp_request(ifp, ifp->gw, NULL);  // unsolicited GW ARP request
   } else if (ifp->state == MG_TCPIP_STATE_UP) {
@@ -4800,6 +4811,7 @@ static void rx_dhcp_client(struct mg_tcpip_if *ifp, struct pkt *pkt) {
       MG_INFO(("Lease: %u sec (%lld)", lease, ifp->lease_expire / 1000));
       // assume DHCP server = router until ARP resolves
       memcpy(ifp->gwmac, pkt->eth->src, sizeof(ifp->gwmac));
+      if (ifp->ip != ip) ifp->is_ip_changed = true;
       ifp->ip = ip, ifp->gw = gw, ifp->mask = mask;
       ifp->state = MG_TCPIP_STATE_IP;  // BOUND state
       mg_random(&rand, sizeof(rand));
@@ -5012,15 +5024,15 @@ static bool fill_global(uint64_t *ip6, uint8_t *prefix, uint8_t prefix_len,
                         uint8_t *mac) {
   uint8_t full = prefix_len / 8;
   uint8_t rem = prefix_len % 8;
-  if (full >= 8 && rem != 0) {
+  if (full > 8 || (full == 8 && rem != 0)) {
     MG_ERROR(("Prefix length > 64, UNSUPPORTED"));
     return false;
   } else if (full == 8 && rem == 0) {
     ip6gen((uint8_t *) ip6, prefix, mac);
   } else {
     ip6[0] = ip6[1] = 0;  // already zeroed before firing RS...
-    if (full) memcpy(ip6, prefix, full);
-    if (rem) {
+    if (full > 0) memcpy(ip6, prefix, full);
+    if (rem > 0) {
       uint8_t mask = (uint8_t) (0xFF << (8 - rem));
       ((uint8_t *) ip6)[full] = prefix[full] & mask;
     }
@@ -5029,6 +5041,27 @@ static bool fill_global(uint64_t *ip6, uint8_t *prefix, uint8_t prefix_len,
   return true;
 }
 
+static bool match_prefix(uint8_t *new, uint8_t len, uint8_t *cur,
+                         uint8_t *cur_len) {
+  uint8_t full = len / 8;
+  uint8_t rem = len % 8;
+  bool res = true;
+  if (full > 8 || (full == 8 && rem != 0))
+    return false;  // Prefix length > 64: UNSUPPORTED
+  if (*cur_len != len) res = false;
+  if (full > 0) {
+    if (res && memcmp(cur, new, full) != 0) res = false;
+    memcpy(cur, new, full);
+  }
+  if (rem > 0) {
+    uint8_t mask = (uint8_t) (0xFF << (8 - rem));
+    if (res && cur[full] != (new[full] & mask)) res = false;
+    cur[full] = new[full] & mask;
+  }
+  *cur_len = len;
+  return res;
+}
+
 // Router Advertisement, 4.2
 static void rx_ndp_ra(struct mg_tcpip_if *ifp, struct pkt *pkt) {
   if (pkt->pay.len < 12) return;
@@ -5063,14 +5096,13 @@ static void rx_ndp_ra(struct mg_tcpip_if *ifp, struct pkt *pkt) {
         uint8_t *prefix = opts + 16;
 
         // TODO (robertc2000): handle prefix options if necessary
-        (void) prefix_len;
         (void) pfx_flags;
         (void) valid;
         (void) pref_lifetime;
-        (void) prefix;
 
-        // fill prefix length and global
-        ifp->prefix_len = prefix_len;
+        // fill prefix and global address
+        if (!match_prefix(prefix, prefix_len, ifp->prefix, &ifp->prefix_len))
+          ifp->is_ip6_changed = true;
         if (!fill_global(ifp->ip6, prefix, prefix_len, ifp->mac)) return;
       }
       opts += length;
@@ -5113,10 +5145,21 @@ static void rx_icmp6(struct mg_tcpip_if *ifp, struct pkt *pkt) {
 }
 
 static void onstate6change(struct mg_tcpip_if *ifp) {
+  struct mg_connection *c;
   if (ifp->state6 == MG_TCPIP_STATE_READY) {
     MG_INFO(("READY, IP: %M", mg_print_ip6, &ifp->ip6));
     MG_INFO(("       GW: %M", mg_print_ip6, &ifp->gw6));
     MG_INFO(("      MAC: %M", mg_print_mac, &ifp->mac));
+    for (c = ifp->mgr->conns; c != NULL; c = c->next) {
+      if (ifp->is_ip6_changed) {
+        if (c->is_listening || c->is_udp) {
+          c->loc.ip6[0] = ifp->ip6[0], c->loc.ip6[1] = ifp->ip6[1];
+        } else {
+          c->is_closing = 1;
+        }
+      }
+    }
+    ifp->is_ip6_changed = false;
   } else if (ifp->state6 == MG_TCPIP_STATE_IP) {
     tx_ndp_ns(ifp, ifp->gw6, ifp->gw6mac);  // unsolicited GW MAC resolution
   } else if (ifp->state6 == MG_TCPIP_STATE_UP) {
@@ -5603,10 +5646,10 @@ static void rx_ip(struct mg_tcpip_if *ifp, struct pkt *pkt) {
   if (ihl < 5) return;                              // bad IHL
   if (pkt->pay.len < (uint16_t) (ihl * 4)) return;  // Truncated / malformed
   // There can be link padding, take length from IP header
-  len = mg_ntohs(pkt->ip->len);                       // IP datagram length
+  len = mg_ntohs(pkt->ip->len);  // IP datagram length
   if (len < (uint16_t) (ihl * 4) || len > pkt->pay.len) return;  // malformed
-  pkt->pay.len = len;                                 // strip padding
-  mkpay(pkt, (uint32_t *) pkt->ip + ihl);             // account for opts
+  pkt->pay.len = len;                      // strip padding
+  mkpay(pkt, (uint32_t *) pkt->ip + ihl);  // account for opts
   frag = mg_ntohs(pkt->ip->frag);
   if (frag & IP_MORE_FRAGS_MSK || frag & IP_FRAG_OFFSET_MSK) {
     struct mg_connection *c;
@@ -25213,15 +25256,11 @@ enum {
   EPHYSTS = 16
 };  // PHY constants
 
-static inline void tm4cspin(volatile uint32_t count) {
-  while (count--) (void) 0;
-}
-
 static uint32_t emac_read_phy(uint8_t addr, uint8_t reg) {
   EMAC->EMACMIIADDR &= (0xf << 2);
   EMAC->EMACMIIADDR |= ((uint32_t) addr << 11) | ((uint32_t) reg << 6);
   EMAC->EMACMIIADDR |= MG_BIT(0);
-  while (EMAC->EMACMIIADDR & MG_BIT(0)) tm4cspin(1);
+  while (EMAC->EMACMIIADDR & MG_BIT(0)) (void) 0;
   return EMAC->EMACMIIDATA;
 }
 
@@ -25231,7 +25270,7 @@ static void emac_write_phy(uint8_t addr, uint8_t reg, uint32_t val) {
   EMAC->EMACMIIADDR |=
       ((uint32_t) addr << 11) | ((uint32_t) reg << 6) | MG_BIT(1);
   EMAC->EMACMIIADDR |= MG_BIT(0);
-  while (EMAC->EMACMIIADDR & MG_BIT(0)) tm4cspin(1);
+  while (EMAC->EMACMIIADDR & MG_BIT(0)) (void) 0;
 }
 
 static uint32_t get_sysclk(void) {
@@ -25323,9 +25362,8 @@ static bool mg_tcpip_driver_tm4c_init(struct mg_tcpip_if *ifp) {
         (uint32_t) (uintptr_t) s_txdesc[(i + 1) % ETH_DESC_CNT];  // Chain
   }
 
-  EMAC->EMACDMABUSMOD |= MG_BIT(0);  // Software reset
-  while ((EMAC->EMACDMABUSMOD & MG_BIT(0)) != 0)
-    tm4cspin(1);  // Wait until done
+  EMAC->EMACDMABUSMOD |= MG_BIT(0);                         // Software reset
+  while ((EMAC->EMACDMABUSMOD & MG_BIT(0)) != 0) (void) 0;  // Wait until done
 
   // Set MDC clock divider. If user told us the value, use it. Otherwise, guess
   int cr = (d == NULL || d->mdc_cr < 0) ? guess_mdc_cr() : d->mdc_cr;
diff --git a/mongoose.h b/mongoose.h
index 5592d83dbe..91ba8a38f3 100644
--- a/mongoose.h
+++ b/mongoose.h
@@ -3135,17 +3135,20 @@ typedef void (*mg_tcpip_event_handler_t)(struct mg_tcpip_if *ifp, int ev,
                                          void *ev_data);
 
 enum {
-  MG_TCPIP_EV_ST_CHG,           // state change                   uint8_t * (&ifp->state)
-  MG_TCPIP_EV_DHCP_DNS,         // DHCP DNS assignment            uint32_t *ipaddr
-  MG_TCPIP_EV_DHCP_SNTP,        // DHCP SNTP assignment           uint32_t *ipaddr
-  MG_TCPIP_EV_ARP,              // Got ARP packet                 struct mg_str *
-  MG_TCPIP_EV_TIMER_1S,         // 1 second timer                 NULL
-  MG_TCPIP_EV_WIFI_SCAN_RESULT, // Wi-Fi scan results             struct mg_wifi_scan_bss_data *
-  MG_TCPIP_EV_WIFI_SCAN_END,    // Wi-Fi scan has finished        NULL
-  MG_TCPIP_EV_WIFI_CONNECT_ERR, // Wi-Fi connect has failed       driver and chip specific
-  MG_TCPIP_EV_DRIVER,           // Driver event                   driver specific
-  MG_TCPIP_EV_ST6_CHG,          // state6 change                  uint8_t * (&ifp->state6)
-  MG_TCPIP_EV_USER              // Starting ID for user events
+  MG_TCPIP_EV_ST_CHG,  // state change                   uint8_t * (&ifp->state)
+  MG_TCPIP_EV_DHCP_DNS,   // DHCP DNS assignment            uint32_t *ipaddr
+  MG_TCPIP_EV_DHCP_SNTP,  // DHCP SNTP assignment           uint32_t *ipaddr
+  MG_TCPIP_EV_ARP,        // Got ARP packet                 struct mg_str *
+  MG_TCPIP_EV_TIMER_1S,   // 1 second timer                 NULL
+  MG_TCPIP_EV_WIFI_SCAN_RESULT,  // Wi-Fi scan results             struct
+                                 // mg_wifi_scan_bss_data *
+  MG_TCPIP_EV_WIFI_SCAN_END,     // Wi-Fi scan has finished        NULL
+  MG_TCPIP_EV_WIFI_CONNECT_ERR,  // Wi-Fi connect has failed       driver and
+                                 // chip specific
+  MG_TCPIP_EV_DRIVER,   // Driver event                   driver specific
+  MG_TCPIP_EV_ST6_CHG,  // state6 change                  uint8_t *
+                        // (&ifp->state6)
+  MG_TCPIP_EV_USER      // Starting ID for user events
 };
 
 // Network interface
@@ -3161,6 +3164,7 @@ struct mg_tcpip_if {
   bool enable_crc32_check;         // Do a CRC check on RX frames and strip it
   bool enable_mac_check;           // Do a MAC check on RX frames
   bool update_mac_hash_table;      // Signal drivers to update MAC controller
+  bool is_ip_changed;              // IP address changed, close/restart conns
   struct mg_tcpip_driver *driver;  // Low level driver
   void *driver_data;               // Driver-specific data
   mg_tcpip_event_handler_t pfn;    // Driver-specific event handler function
@@ -3171,11 +3175,13 @@ struct mg_tcpip_if {
   uint16_t mtu;                            // Interface MTU
 #define MG_TCPIP_MTU_DEFAULT 1500
 #if MG_ENABLE_IPV6
-  uint64_t ip6ll[2], ip6[2];       // IPv6 link-local and global addresses
-  uint8_t prefix_len;              // Prefix length
-  uint64_t gw6[2];                 // Default gateway
-  bool enable_slaac;               // Enable IPv6 address autoconfiguration
-  bool enable_dhcp6_client;        // Enable DCHPv6 client
+  uint64_t ip6ll[2], ip6[2];  // IPv6 link-local and global addresses
+  uint8_t prefix[8];          // IPv6 global address prefix
+  uint8_t prefix_len;         // Prefix length
+  uint64_t gw6[2];            // Default gateway
+  bool enable_slaac;          // Enable IPv6 address autoconfiguration
+  bool enable_dhcp6_client;   // Enable DCHPv6 client
+  bool is_ip6_changed;        // IPv6 address changed, close/restart conns
 #endif
 
   // Internal state, user can use it but should not change it
@@ -3196,8 +3202,8 @@ struct mg_tcpip_if {
 #define MG_TCPIP_STATE_IP 3     // Interface is up and has an IP assigned
 #define MG_TCPIP_STATE_READY 4  // Interface has fully come up, ready to work
 #if MG_ENABLE_IPV6
-  uint8_t gw6mac[6];             // IPv6 Router's MAC
-  uint8_t state6;                // Current IPv6 state
+  uint8_t gw6mac[6];  // IPv6 Router's MAC
+  uint8_t state6;     // Current IPv6 state
 #endif
 };
 void mg_tcpip_init(struct mg_mgr *, struct mg_tcpip_if *);
@@ -3231,39 +3237,38 @@ struct mg_tcpip_spi {
   uint8_t (*txn)(void *, uint8_t);  // SPI transaction: write 1 byte, read reply
 };
 
-
 // Alignment and memory section requirements
 #ifndef MG_8BYTE_ALIGNED
 #if defined(__GNUC__)
 #define MG_8BYTE_ALIGNED __attribute__((aligned((8U))))
 #else
 #define MG_8BYTE_ALIGNED
-#endif // compiler
-#endif // 8BYTE_ALIGNED
+#endif  // compiler
+#endif  // 8BYTE_ALIGNED
 
 #ifndef MG_16BYTE_ALIGNED
 #if defined(__GNUC__)
 #define MG_16BYTE_ALIGNED __attribute__((aligned((16U))))
 #else
 #define MG_16BYTE_ALIGNED
-#endif // compiler
-#endif // 16BYTE_ALIGNED
+#endif  // compiler
+#endif  // 16BYTE_ALIGNED
 
 #ifndef MG_32BYTE_ALIGNED
 #if defined(__GNUC__)
 #define MG_32BYTE_ALIGNED __attribute__((aligned((32U))))
 #else
 #define MG_32BYTE_ALIGNED
-#endif // compiler
-#endif // 32BYTE_ALIGNED
+#endif  // compiler
+#endif  // 32BYTE_ALIGNED
 
 #ifndef MG_64BYTE_ALIGNED
 #if defined(__GNUC__)
 #define MG_64BYTE_ALIGNED __attribute__((aligned((64U))))
 #else
 #define MG_64BYTE_ALIGNED
-#endif // compiler
-#endif // 64BYTE_ALIGNED
+#endif  // compiler
+#endif  // 64BYTE_ALIGNED
 
 #ifndef MG_ETH_RAM
 #define MG_ETH_RAM
diff --git a/src/drivers/tm4c.c b/src/drivers/tm4c.c
index 31efafad4a..a7adb1a474 100644
--- a/src/drivers/tm4c.c
+++ b/src/drivers/tm4c.c
@@ -40,15 +40,11 @@ enum {
   EPHYSTS = 16
 };  // PHY constants
 
-static inline void tm4cspin(volatile uint32_t count) {
-  while (count--) (void) 0;
-}
-
 static uint32_t emac_read_phy(uint8_t addr, uint8_t reg) {
   EMAC->EMACMIIADDR &= (0xf << 2);
   EMAC->EMACMIIADDR |= ((uint32_t) addr << 11) | ((uint32_t) reg << 6);
   EMAC->EMACMIIADDR |= MG_BIT(0);
-  while (EMAC->EMACMIIADDR & MG_BIT(0)) tm4cspin(1);
+  while (EMAC->EMACMIIADDR & MG_BIT(0)) (void) 0;
   return EMAC->EMACMIIDATA;
 }
 
@@ -58,7 +54,7 @@ static void emac_write_phy(uint8_t addr, uint8_t reg, uint32_t val) {
   EMAC->EMACMIIADDR |=
       ((uint32_t) addr << 11) | ((uint32_t) reg << 6) | MG_BIT(1);
   EMAC->EMACMIIADDR |= MG_BIT(0);
-  while (EMAC->EMACMIIADDR & MG_BIT(0)) tm4cspin(1);
+  while (EMAC->EMACMIIADDR & MG_BIT(0)) (void) 0;
 }
 
 static uint32_t get_sysclk(void) {
@@ -150,9 +146,8 @@ static bool mg_tcpip_driver_tm4c_init(struct mg_tcpip_if *ifp) {
         (uint32_t) (uintptr_t) s_txdesc[(i + 1) % ETH_DESC_CNT];  // Chain
   }
 
-  EMAC->EMACDMABUSMOD |= MG_BIT(0);  // Software reset
-  while ((EMAC->EMACDMABUSMOD & MG_BIT(0)) != 0)
-    tm4cspin(1);  // Wait until done
+  EMAC->EMACDMABUSMOD |= MG_BIT(0);                         // Software reset
+  while ((EMAC->EMACDMABUSMOD & MG_BIT(0)) != 0) (void) 0;  // Wait until done
 
   // Set MDC clock divider. If user told us the value, use it. Otherwise, guess
   int cr = (d == NULL || d->mdc_cr < 0) ? guess_mdc_cr() : d->mdc_cr;
diff --git a/src/net_builtin.c b/src/net_builtin.c
index 29a1f6b1aa..ff842d9f7c 100644
--- a/src/net_builtin.c
+++ b/src/net_builtin.c
@@ -305,9 +305,20 @@ void mg_tcpip_arp_request(struct mg_tcpip_if *ifp, uint32_t ip, uint8_t *mac) {
 
 static void onstatechange(struct mg_tcpip_if *ifp) {
   if (ifp->state == MG_TCPIP_STATE_READY) {
+    struct mg_connection *c;
     MG_INFO(("READY, IP: %M", mg_print_ip4, &ifp->ip));
     MG_INFO(("       GW: %M", mg_print_ip4, &ifp->gw));
     MG_INFO(("      MAC: %M", mg_print_mac, &ifp->mac));
+    for (c = ifp->mgr->conns; c != NULL; c = c->next) {
+      if (ifp->is_ip_changed) {
+        if (c->is_listening || c->is_udp) {
+          c->loc.ip4 = c->mgr->ifp->ip;
+        } else {
+          c->is_closing = 1;
+        }
+      }
+    }
+    ifp->is_ip_changed = false;
   } else if (ifp->state == MG_TCPIP_STATE_IP) {
     mg_tcpip_arp_request(ifp, ifp->gw, NULL);  // unsolicited GW ARP request
   } else if (ifp->state == MG_TCPIP_STATE_UP) {
@@ -594,6 +605,7 @@ static void rx_dhcp_client(struct mg_tcpip_if *ifp, struct pkt *pkt) {
       MG_INFO(("Lease: %u sec (%lld)", lease, ifp->lease_expire / 1000));
       // assume DHCP server = router until ARP resolves
       memcpy(ifp->gwmac, pkt->eth->src, sizeof(ifp->gwmac));
+      if (ifp->ip != ip) ifp->is_ip_changed = true;
       ifp->ip = ip, ifp->gw = gw, ifp->mask = mask;
       ifp->state = MG_TCPIP_STATE_IP;  // BOUND state
       mg_random(&rand, sizeof(rand));
@@ -806,15 +818,15 @@ static bool fill_global(uint64_t *ip6, uint8_t *prefix, uint8_t prefix_len,
                         uint8_t *mac) {
   uint8_t full = prefix_len / 8;
   uint8_t rem = prefix_len % 8;
-  if (full >= 8 && rem != 0) {
+  if (full > 8 || (full == 8 && rem != 0)) {
     MG_ERROR(("Prefix length > 64, UNSUPPORTED"));
     return false;
   } else if (full == 8 && rem == 0) {
     ip6gen((uint8_t *) ip6, prefix, mac);
   } else {
     ip6[0] = ip6[1] = 0;  // already zeroed before firing RS...
-    if (full) memcpy(ip6, prefix, full);
-    if (rem) {
+    if (full > 0) memcpy(ip6, prefix, full);
+    if (rem > 0) {
       uint8_t mask = (uint8_t) (0xFF << (8 - rem));
       ((uint8_t *) ip6)[full] = prefix[full] & mask;
     }
@@ -823,6 +835,27 @@ static bool fill_global(uint64_t *ip6, uint8_t *prefix, uint8_t prefix_len,
   return true;
 }
 
+static bool match_prefix(uint8_t *new, uint8_t len, uint8_t *cur,
+                         uint8_t *cur_len) {
+  uint8_t full = len / 8;
+  uint8_t rem = len % 8;
+  bool res = true;
+  if (full > 8 || (full == 8 && rem != 0))
+    return false;  // Prefix length > 64: UNSUPPORTED
+  if (*cur_len != len) res = false;
+  if (full > 0) {
+    if (res && memcmp(cur, new, full) != 0) res = false;
+    memcpy(cur, new, full);
+  }
+  if (rem > 0) {
+    uint8_t mask = (uint8_t) (0xFF << (8 - rem));
+    if (res && cur[full] != (new[full] & mask)) res = false;
+    cur[full] = new[full] & mask;
+  }
+  *cur_len = len;
+  return res;
+}
+
 // Router Advertisement, 4.2
 static void rx_ndp_ra(struct mg_tcpip_if *ifp, struct pkt *pkt) {
   if (pkt->pay.len < 12) return;
@@ -857,14 +890,13 @@ static void rx_ndp_ra(struct mg_tcpip_if *ifp, struct pkt *pkt) {
         uint8_t *prefix = opts + 16;
 
         // TODO (robertc2000): handle prefix options if necessary
-        (void) prefix_len;
         (void) pfx_flags;
         (void) valid;
         (void) pref_lifetime;
-        (void) prefix;
 
-        // fill prefix length and global
-        ifp->prefix_len = prefix_len;
+        // fill prefix and global address
+        if (!match_prefix(prefix, prefix_len, ifp->prefix, &ifp->prefix_len))
+          ifp->is_ip6_changed = true;
         if (!fill_global(ifp->ip6, prefix, prefix_len, ifp->mac)) return;
       }
       opts += length;
@@ -907,10 +939,21 @@ static void rx_icmp6(struct mg_tcpip_if *ifp, struct pkt *pkt) {
 }
 
 static void onstate6change(struct mg_tcpip_if *ifp) {
+  struct mg_connection *c;
   if (ifp->state6 == MG_TCPIP_STATE_READY) {
     MG_INFO(("READY, IP: %M", mg_print_ip6, &ifp->ip6));
     MG_INFO(("       GW: %M", mg_print_ip6, &ifp->gw6));
     MG_INFO(("      MAC: %M", mg_print_mac, &ifp->mac));
+    for (c = ifp->mgr->conns; c != NULL; c = c->next) {
+      if (ifp->is_ip6_changed) {
+        if (c->is_listening || c->is_udp) {
+          c->loc.ip6[0] = ifp->ip6[0], c->loc.ip6[1] = ifp->ip6[1];
+        } else {
+          c->is_closing = 1;
+        }
+      }
+    }
+    ifp->is_ip6_changed = false;
   } else if (ifp->state6 == MG_TCPIP_STATE_IP) {
     tx_ndp_ns(ifp, ifp->gw6, ifp->gw6mac);  // unsolicited GW MAC resolution
   } else if (ifp->state6 == MG_TCPIP_STATE_UP) {
@@ -1397,10 +1440,10 @@ static void rx_ip(struct mg_tcpip_if *ifp, struct pkt *pkt) {
   if (ihl < 5) return;                              // bad IHL
   if (pkt->pay.len < (uint16_t) (ihl * 4)) return;  // Truncated / malformed
   // There can be link padding, take length from IP header
-  len = mg_ntohs(pkt->ip->len);                       // IP datagram length
+  len = mg_ntohs(pkt->ip->len);  // IP datagram length
   if (len < (uint16_t) (ihl * 4) || len > pkt->pay.len) return;  // malformed
-  pkt->pay.len = len;                                 // strip padding
-  mkpay(pkt, (uint32_t *) pkt->ip + ihl);             // account for opts
+  pkt->pay.len = len;                      // strip padding
+  mkpay(pkt, (uint32_t *) pkt->ip + ihl);  // account for opts
   frag = mg_ntohs(pkt->ip->frag);
   if (frag & IP_MORE_FRAGS_MSK || frag & IP_FRAG_OFFSET_MSK) {
     struct mg_connection *c;
diff --git a/src/net_builtin.h b/src/net_builtin.h
index ec88f51c59..b762e875cf 100644
--- a/src/net_builtin.h
+++ b/src/net_builtin.h
@@ -20,17 +20,20 @@ typedef void (*mg_tcpip_event_handler_t)(struct mg_tcpip_if *ifp, int ev,
                                          void *ev_data);
 
 enum {
-  MG_TCPIP_EV_ST_CHG,           // state change                   uint8_t * (&ifp->state)
-  MG_TCPIP_EV_DHCP_DNS,         // DHCP DNS assignment            uint32_t *ipaddr
-  MG_TCPIP_EV_DHCP_SNTP,        // DHCP SNTP assignment           uint32_t *ipaddr
-  MG_TCPIP_EV_ARP,              // Got ARP packet                 struct mg_str *
-  MG_TCPIP_EV_TIMER_1S,         // 1 second timer                 NULL
-  MG_TCPIP_EV_WIFI_SCAN_RESULT, // Wi-Fi scan results             struct mg_wifi_scan_bss_data *
-  MG_TCPIP_EV_WIFI_SCAN_END,    // Wi-Fi scan has finished        NULL
-  MG_TCPIP_EV_WIFI_CONNECT_ERR, // Wi-Fi connect has failed       driver and chip specific
-  MG_TCPIP_EV_DRIVER,           // Driver event                   driver specific
-  MG_TCPIP_EV_ST6_CHG,          // state6 change                  uint8_t * (&ifp->state6)
-  MG_TCPIP_EV_USER              // Starting ID for user events
+  MG_TCPIP_EV_ST_CHG,  // state change                   uint8_t * (&ifp->state)
+  MG_TCPIP_EV_DHCP_DNS,   // DHCP DNS assignment            uint32_t *ipaddr
+  MG_TCPIP_EV_DHCP_SNTP,  // DHCP SNTP assignment           uint32_t *ipaddr
+  MG_TCPIP_EV_ARP,        // Got ARP packet                 struct mg_str *
+  MG_TCPIP_EV_TIMER_1S,   // 1 second timer                 NULL
+  MG_TCPIP_EV_WIFI_SCAN_RESULT,  // Wi-Fi scan results             struct
+                                 // mg_wifi_scan_bss_data *
+  MG_TCPIP_EV_WIFI_SCAN_END,     // Wi-Fi scan has finished        NULL
+  MG_TCPIP_EV_WIFI_CONNECT_ERR,  // Wi-Fi connect has failed       driver and
+                                 // chip specific
+  MG_TCPIP_EV_DRIVER,   // Driver event                   driver specific
+  MG_TCPIP_EV_ST6_CHG,  // state6 change                  uint8_t *
+                        // (&ifp->state6)
+  MG_TCPIP_EV_USER      // Starting ID for user events
 };
 
 // Network interface
@@ -46,6 +49,7 @@ struct mg_tcpip_if {
   bool enable_crc32_check;         // Do a CRC check on RX frames and strip it
   bool enable_mac_check;           // Do a MAC check on RX frames
   bool update_mac_hash_table;      // Signal drivers to update MAC controller
+  bool is_ip_changed;              // IP address changed, close/restart conns
   struct mg_tcpip_driver *driver;  // Low level driver
   void *driver_data;               // Driver-specific data
   mg_tcpip_event_handler_t pfn;    // Driver-specific event handler function
@@ -56,11 +60,13 @@ struct mg_tcpip_if {
   uint16_t mtu;                            // Interface MTU
 #define MG_TCPIP_MTU_DEFAULT 1500
 #if MG_ENABLE_IPV6
-  uint64_t ip6ll[2], ip6[2];       // IPv6 link-local and global addresses
-  uint8_t prefix_len;              // Prefix length
-  uint64_t gw6[2];                 // Default gateway
-  bool enable_slaac;               // Enable IPv6 address autoconfiguration
-  bool enable_dhcp6_client;        // Enable DCHPv6 client
+  uint64_t ip6ll[2], ip6[2];  // IPv6 link-local and global addresses
+  uint8_t prefix[8];          // IPv6 global address prefix
+  uint8_t prefix_len;         // Prefix length
+  uint64_t gw6[2];            // Default gateway
+  bool enable_slaac;          // Enable IPv6 address autoconfiguration
+  bool enable_dhcp6_client;   // Enable DCHPv6 client
+  bool is_ip6_changed;        // IPv6 address changed, close/restart conns
 #endif
 
   // Internal state, user can use it but should not change it
@@ -81,8 +87,8 @@ struct mg_tcpip_if {
 #define MG_TCPIP_STATE_IP 3     // Interface is up and has an IP assigned
 #define MG_TCPIP_STATE_READY 4  // Interface has fully come up, ready to work
 #if MG_ENABLE_IPV6
-  uint8_t gw6mac[6];             // IPv6 Router's MAC
-  uint8_t state6;                // Current IPv6 state
+  uint8_t gw6mac[6];  // IPv6 Router's MAC
+  uint8_t state6;     // Current IPv6 state
 #endif
 };
 void mg_tcpip_init(struct mg_mgr *, struct mg_tcpip_if *);
@@ -116,39 +122,38 @@ struct mg_tcpip_spi {
   uint8_t (*txn)(void *, uint8_t);  // SPI transaction: write 1 byte, read reply
 };
 
-
 // Alignment and memory section requirements
 #ifndef MG_8BYTE_ALIGNED
 #if defined(__GNUC__)
 #define MG_8BYTE_ALIGNED __attribute__((aligned((8U))))
 #else
 #define MG_8BYTE_ALIGNED
-#endif // compiler
-#endif // 8BYTE_ALIGNED
+#endif  // compiler
+#endif  // 8BYTE_ALIGNED
 
 #ifndef MG_16BYTE_ALIGNED
 #if defined(__GNUC__)
 #define MG_16BYTE_ALIGNED __attribute__((aligned((16U))))
 #else
 #define MG_16BYTE_ALIGNED
-#endif // compiler
-#endif // 16BYTE_ALIGNED
+#endif  // compiler
+#endif  // 16BYTE_ALIGNED
 
 #ifndef MG_32BYTE_ALIGNED
 #if defined(__GNUC__)
 #define MG_32BYTE_ALIGNED __attribute__((aligned((32U))))
 #else
 #define MG_32BYTE_ALIGNED
-#endif // compiler
-#endif // 32BYTE_ALIGNED
+#endif  // compiler
+#endif  // 32BYTE_ALIGNED
 
 #ifndef MG_64BYTE_ALIGNED
 #if defined(__GNUC__)
 #define MG_64BYTE_ALIGNED __attribute__((aligned((64U))))
 #else
 #define MG_64BYTE_ALIGNED
-#endif // compiler
-#endif // 64BYTE_ALIGNED
+#endif  // compiler
+#endif  // 64BYTE_ALIGNED
 
 #ifndef MG_ETH_RAM
 #define MG_ETH_RAM
diff --git a/test/mip_test.c b/test/mip_test.c
index 7097b1d1b2..e260299ba1 100644
--- a/test/mip_test.c
+++ b/test/mip_test.c
@@ -56,12 +56,14 @@ static void mif_fn(struct mg_tcpip_if *ifp, int ev, void *ev_data) {
 }
 
 static void test_statechange(void) {
+  struct mg_mgr mgr;
   struct mg_tcpip_if iface;
   memset(&iface, 0, sizeof(iface));
   iface.ip = mg_htonl(0x01020304);
   iface.state = MG_TCPIP_STATE_READY;
   iface.driver = &mg_tcpip_driver_mock;
   iface.fn = mif_fn;
+  iface.mgr = &mgr;
   onstatechange(&iface);
   ASSERT(executed == true);
   executed = false;
@@ -76,6 +78,7 @@ static void mif6_fn(struct mg_tcpip_if *ifp, int ev, void *ev_data) {
 }
 
 static void test_state6change(void) {
+  struct mg_mgr mgr;
   struct mg_tcpip_if iface;
   memset(&iface, 0, sizeof(iface));
   iface.ip6[0] = (uint64_t) mg_htonl(0x01020304);
@@ -83,6 +86,7 @@ static void test_state6change(void) {
   iface.state6 = MG_TCPIP_STATE_READY;
   iface.driver = &mg_tcpip_driver_mock;
   iface.fn = mif6_fn;
+  iface.mgr = &mgr;
   onstate6change(&iface);
   ASSERT(executed == true);
   executed = false;