diff --git a/app/src/main/cpp/baresip.c b/app/src/main/cpp/baresip.c
index 68d663e6..9216b74d 100644
--- a/app/src/main/cpp/baresip.c
+++ b/app/src/main/cpp/baresip.c
@@ -375,11 +375,12 @@ JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM* vm, void* reserved) {
 
 JNIEXPORT void JNICALL
 Java_com_tutpro_baresip_BaresipService_baresipStart(JNIEnv *env, jobject instance,
-        jstring javaPath, jstring javaIpV6Addr, jboolean javaPreferIpV6) {
+        jstring javaPath, jstring javaIpV4Addr, jstring javaIpV6Addr, jboolean javaPreferIpV6) {
 
     LOGD("starting baresip\n");
 
     struct sa temp_sa;
+    const char *ipv4_addr = (*env)->GetStringUTFChars(env, javaIpV4Addr, 0);
     const char *ipv6_addr = (*env)->GetStringUTFChars(env, javaIpV6Addr, 0);
     char start_error[64] = "";
 
@@ -422,13 +423,19 @@ Java_com_tutpro_baresip_BaresipService_baresipStart(JNIEnv *env, jobject instanc
         goto out;
     }
 
+    if (strlen(ipv4_addr) > 0) {
+        sa_set_str(&temp_sa, ipv4_addr, 0);
+        net_set_address(baresip_network(), &temp_sa);
+    }
+
     if (strlen(ipv6_addr) > 0) {
         sa_set_str(&temp_sa, ipv6_addr, 0);
         net_set_address(baresip_network(), &temp_sa);
-        if ((bool)(javaPreferIpV6 == JNI_TRUE))
-            net_set_af(baresip_network(), AF_INET6);
+        net_set_af(baresip_network(), javaPreferIpV6 == JNI_TRUE ? AF_INET6 : AF_INET);
     }
 
+    net_debug_log();
+
     play_set_path(baresip_player(), path);
 
     err = ua_init("baresip v" BARESIP_VERSION " (" ARCH "/" OS ")",
@@ -484,7 +491,6 @@ Java_com_tutpro_baresip_BaresipService_baresipStart(JNIEnv *env, jobject instanc
         goto out;
     }
 
-    net_debug_log();
     for (le = list_head(uag_list()); le != NULL; le = le->next)
         ua_print_status_log(le->data);
 
@@ -492,8 +498,8 @@ Java_com_tutpro_baresip_BaresipService_baresipStart(JNIEnv *env, jobject instanc
     err = re_main(signal_handler);
 
     out:
-
-    (*env)->ReleaseStringUTFChars(env, javaIpV6Addr, ipv6_addr);
+        (*env)->ReleaseStringUTFChars(env, javaIpV4Addr, ipv4_addr);
+        (*env)->ReleaseStringUTFChars(env, javaIpV6Addr, ipv6_addr);
 
     if (err) {
         LOGE("stopping UAs due to error: (%d)\n", err);
@@ -1417,6 +1423,18 @@ Java_com_tutpro_baresip_Api_net_1set_1address(JNIEnv *env, jobject thiz, jstring
     return res;
 }
 
+JNIEXPORT void JNICALL
+Java_com_tutpro_baresip_Api_net_1unset_1address(JNIEnv *env, jobject thiz, jboolean javaIpV6) {
+    int res = 0;
+    struct sa temp_sa;
+    LOGD("unsetting %s address\n", javaIpV6 == JNI_TRUE ? "IPv6" : "IpV4");
+    if (javaIpV6 == JNI_TRUE)
+        sa_init(&temp_sa, AF_INET6);
+    else
+        sa_init(&temp_sa, AF_INET);
+    net_set_address(baresip_network(), &temp_sa);
+}
+
 JNIEXPORT jboolean JNICALL
 Java_com_tutpro_baresip_Api_net_1set_1af(JNIEnv *env, jobject thiz, jboolean javaIpV6) {
     int af = javaIpV6 == JNI_TRUE ? AF_INET6 : AF_INET;
diff --git a/app/src/main/kotlin/com/tutpro/baresip/Api.kt b/app/src/main/kotlin/com/tutpro/baresip/Api.kt
index 8516333c..ec53768a 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/Api.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/Api.kt
@@ -33,6 +33,7 @@ object Api {
     external fun log_level_set(level: Int)
     external fun net_use_nameserver(servers: String): Int
     external fun net_set_address(ip_addr: String): Int
+    external fun net_unset_address(ipv6: Boolean)
     external fun net_set_af(ipv6: Boolean): Boolean
     external fun net_force_change()
     external fun net_debug()
diff --git a/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt b/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt
index a0c7ce68..51c086aa 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/BaresipService.kt
@@ -79,19 +79,33 @@ class BaresipService: Service() {
 
                     override fun onAvailable(network: Network) {
                         super.onAvailable(network)
-                        Log.i(LOG_TAG, "Network '${cm.getLinkProperties(network)}' is available")
-                        dnsServers = cm.getLinkProperties(network).dnsServers
-                        linkAddresses = cm.getLinkProperties(network).linkAddresses
+                        val linkProperties = cm.getLinkProperties(network)
+                        Log.i(LOG_TAG, "Network $network is available: '$linkProperties'")
+                        dnsServers = linkProperties.dnsServers
+                        linkAddresses = linkProperties.linkAddresses
                     }
 
                     override fun onLost(network: Network) {
                         super.onLost(network)
                         Log.d(LOG_TAG, "Network '$network' is lost")
+                        val allNetworks = cm.allNetworks
+                        if (allNetworks.size > 0) {
+                            Log.d(LOG_TAG, "Network ${allNetworks[0]} is available")
+                            val linkProperties = cm.getLinkProperties(allNetworks[0])
+                            if (dynDns) {
+                                dnsServers = linkProperties.dnsServers
+                                if (Config.updateDnsServers(dnsServers) != 0)
+                                    Log.w(LOG_TAG, "Failed to update DNS servers '$dnsServers'")
+                            }
+                            linkAddresses = linkProperties.linkAddresses
+                            Utils.updateLinkAddresses()
+                            UserAgent.register()
+                        }
                     }
 
                     override fun onLinkPropertiesChanged(network: Network, linkProperties: LinkProperties) {
                         super.onLinkPropertiesChanged(network, linkProperties)
-                        Log.e(LOG_TAG, "Network link properties changed: $linkProperties")
+                        Log.e(LOG_TAG, "Network $network link properties changed: $linkProperties")
                         if (!isServiceRunning)
                             return
                         if (dynDns) {
@@ -99,28 +113,8 @@ class BaresipService: Service() {
                             if (Config.updateDnsServers(dnsServers) != 0)
                                 Log.w(LOG_TAG, "Failed to update DNS servers '$dnsServers'")
                         }
-                        val ipV6Addr = Utils.findIpV6Address(linkProperties.linkAddresses)
-                        if (ipV6Addr != "") {
-                            Log.w(LOG_TAG, "Found IPv6 address '$ipV6Addr'")
-                            if (Api.net_set_address(ipV6Addr) != 0) {
-                                Log.w(LOG_TAG, "Failed to update net address '$ipV6Addr'")
-                            } else {
-                                if (preferIpV6)
-                                    Api.net_set_af(true)
-                            }
-                        }
-                        val ipV4Addr = Utils.findIpV4Address(linkProperties.linkAddresses)
-                        if (ipV4Addr != "") {
-                            Log.w(LOG_TAG, "Found IPv4 address '$ipV4Addr'")
-                            if (Api.net_set_address(ipV4Addr) != 0) {
-                                Log.w(LOG_TAG, "Failed to update net address '$ipV4Addr'")
-                            } else {
-                                if (!preferIpV6 || (ipV6Addr == ""))
-                                    Api.net_set_af(false)
-                            }
-                        }
-                        Api.net_force_change()
-                        Api.net_debug()
+                        linkAddresses = linkProperties.linkAddresses
+                        Utils.updateLinkAddresses()
                         // UserAgent.register()
                     }
                 }
@@ -267,6 +261,7 @@ class BaresipService: Service() {
                 Message.restore()
 
                 Thread(Runnable { baresipStart(filesPath,
+                        Utils.findIpV4Address(linkAddresses),
                         Utils.findIpV6Address(linkAddresses),
                         preferIpV6) }).start()
 
@@ -1016,7 +1011,7 @@ class BaresipService: Service() {
         isServiceClean = true
     }
 
-    external fun baresipStart(path: String, ipV6Addr: String, preferIpV6: Boolean)
+    external fun baresipStart(path: String, ipV4Addr: String, ipV6Addr: String, preferIpV6: Boolean)
     external fun baresipStop(force: Boolean)
 
     companion object {
diff --git a/app/src/main/kotlin/com/tutpro/baresip/ConfigActivity.kt b/app/src/main/kotlin/com/tutpro/baresip/ConfigActivity.kt
index bd490b21..4f71b91b 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/ConfigActivity.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/ConfigActivity.kt
@@ -220,28 +220,7 @@ class ConfigActivity : AppCompatActivity() {
                 if (oldPreferIPv6 != preferIPv6String) {
                     Config.replaceVariable("prefer_ipv6", preferIPv6String)
                     BaresipService.preferIpV6 = preferIPv6String == "yes"
-                    if (preferIPv6String == "yes") {
-                        val ipV6Addr = Utils.findIpV6Address(BaresipService.linkAddresses)
-                        if (ipV6Addr != "") {
-                            if (Api.net_set_address(ipV6Addr) != 0) {
-                                Log.w("Baresip", "Failed to update net address '$ipV6Addr'")
-                            } else {
-                                Api.net_set_af(true)
-                                Api.net_force_change()
-                            }
-                        }
-                    } else {
-                        val ipV4Addr = Utils.findIpV4Address(BaresipService.linkAddresses)
-                        if (ipV4Addr != "") {
-                            if (Api.net_set_address(ipV4Addr) != 0) {
-                                Log.w("Baresip", "Failed to update net address '$ipV4Addr'")
-                            } else {
-                                Api.net_set_af(false)
-                                Api.net_force_change()
-                            }
-                        }
-                    }
-                    Api.net_debug()
+                    Utils.updateLinkAddresses()
                     save = true
                 }
 
diff --git a/app/src/main/kotlin/com/tutpro/baresip/Utils.kt b/app/src/main/kotlin/com/tutpro/baresip/Utils.kt
index 56ed412d..2d3e6dc5 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/Utils.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/Utils.kt
@@ -244,6 +244,36 @@ object Utils {
         return ""
     }
 
+    fun updateLinkAddresses() {
+        val ipV6Addr = findIpV6Address(BaresipService.linkAddresses)
+        if (ipV6Addr != "") {
+            Log.d("Baresip", "Found IPv6 address '$ipV6Addr'")
+            if (Api.net_set_address(ipV6Addr) != 0) {
+                Log.w("Baresip", "Failed to update net address '$ipV6Addr'")
+            } else {
+                Api.net_set_af(BaresipService.preferIpV6)
+            }
+        } else {
+            Api.net_unset_address(true)
+            Api.net_set_af(false)
+        }
+        val ipV4Addr = findIpV4Address(BaresipService.linkAddresses)
+        if (ipV4Addr != "") {
+            Log.w("Baresip", "Found IPv4 address '$ipV4Addr'")
+            if (Api.net_set_address(ipV4Addr) != 0) {
+                Log.w("Baresip", "Failed to update net address '$ipV4Addr'")
+            } else {
+                if (!BaresipService.preferIpV6 || (ipV6Addr == ""))
+                    Api.net_set_af(false)
+            }
+        } else {
+            Api.net_unset_address(false)
+            Api.net_set_af(false)
+        }
+        Api.net_force_change()
+        Api.net_debug()
+    }
+
     fun implode(list: List<String>, sep: String): String {
         var res = ""
         for (s in list) {