diff --git a/auto_tests/TCP_test.c b/auto_tests/TCP_test.c
index cb27d27ff6..4a13ef2481 100644
--- a/auto_tests/TCP_test.c
+++ b/auto_tests/TCP_test.c
@@ -8,6 +8,7 @@
 #include "../toxcore/TCP_server.h"
 #include "../toxcore/crypto_core.h"
 #include "../toxcore/mono_time.h"
+#include "../toxcore/network.h"
 #include "auto_test_support.h"
 
 #define NUM_PORTS 3
@@ -73,8 +74,9 @@ static void test_basic(void)
     for (uint8_t i = 0; i < NUM_PORTS; i++) {
         sock = net_socket(ns, net_family_ipv6(), TOX_SOCK_STREAM, TOX_PROTO_TCP);
         localhost.port = net_htons(ports[i]);
-        bool ret = net_connect(ns, mem, logger, sock, &localhost);
-        ck_assert_msg(ret, "Failed to connect to created TCP relay server on port %d (%d).", ports[i], errno);
+        Net_Err_Connect err;
+        bool ret = net_connect(ns, mem, logger, sock, &localhost, &err);
+        ck_assert_msg(ret, "Failed to connect to created TCP relay server on port %d (%d, %s).", ports[i], errno, net_err_connect_to_string(err));
 
         // Leave open one connection for the next test.
         if (i + 1 < NUM_PORTS) {
@@ -218,8 +220,9 @@ static struct sec_TCP_con *new_tcp_con(const Logger *logger, const Memory *mem,
     localhost.ip = get_loopback();
     localhost.port = net_htons(ports[random_u32(rng) % NUM_PORTS]);
 
-    bool ok = net_connect(ns, mem, logger, sock, &localhost);
-    ck_assert_msg(ok, "Failed to connect to the test TCP relay server.");
+    Net_Err_Connect err;
+    bool ok = net_connect(ns, mem, logger, sock, &localhost, &err);
+    ck_assert_msg(ok, "Failed to connect to the test TCP relay server: %s.", net_err_connect_to_string(err));
 
     uint8_t f_secret_key[CRYPTO_SECRET_KEY_SIZE];
     crypto_new_keypair(rng, sec_c->public_key, f_secret_key);
diff --git a/toxcore/TCP_client.c b/toxcore/TCP_client.c
index 5e13134bec..e80c0622e7 100644
--- a/toxcore/TCP_client.c
+++ b/toxcore/TCP_client.c
@@ -109,11 +109,23 @@ void tcp_con_set_custom_uint(TCP_Client_Connection *con, uint32_t value)
 non_null()
 static bool connect_sock_to(const Network *ns, const Logger *logger, const Memory *mem, Socket sock, const IP_Port *ip_port, const TCP_Proxy_Info *proxy_info)
 {
+    Net_Err_Connect err;
     if (proxy_info->proxy_type != TCP_PROXY_NONE) {
-        return net_connect(ns, mem, logger, sock, &proxy_info->ip_port);
+        net_connect(ns, mem, logger, sock, &proxy_info->ip_port, &err);
     } else {
-        return net_connect(ns, mem, logger, sock, ip_port);
+        net_connect(ns, mem, logger, sock, ip_port, &err);
     }
+    switch (err) {
+        case NET_ERR_CONNECT_OK:
+        case NET_ERR_CONNECT_FAILED: {
+            /* nonblocking socket, connect will never return success */
+            return true;
+        }
+        case NET_ERR_CONNECT_INVALID_FAMILY:
+            return false;
+    }
+    LOGGER_ERROR(logger, "unexpected error code %d from net_connect", err);
+    return false;
 }
 
 /**
diff --git a/toxcore/network.c b/toxcore/network.c
index 673e2732ed..ce1a9cfddc 100644
--- a/toxcore/network.c
+++ b/toxcore/network.c
@@ -2015,7 +2015,21 @@ bool addr_resolve_or_parse_ip(const Network *ns, const Memory *mem, const char *
     return addr_parse_ip(address, to);
 }
 
-bool net_connect(const Network *ns, const Memory *mem, const Logger *log, Socket sock, const IP_Port *ip_port)
+const char *net_err_connect_to_string(Net_Err_Connect err)
+{
+    switch (err) {
+        case NET_ERR_CONNECT_OK:
+            return "NET_ERR_CONNECT_OK";
+        case NET_ERR_CONNECT_FAILED:
+            return "NET_ERR_CONNECT_FAILED";
+        case NET_ERR_CONNECT_INVALID_FAMILY:
+            return "NET_ERR_CONNECT_INVALID_FAMILY";
+    }
+
+    return "<invalid Net_Err_Connect>";
+}
+
+bool net_connect(const Network *ns, const Memory *mem, const Logger *log, Socket sock, const IP_Port *ip_port, Net_Err_Connect *err)
 {
     Network_Addr addr = {{0}};
 
@@ -2037,11 +2051,13 @@ bool net_connect(const Network *ns, const Memory *mem, const Logger *log, Socket
         Ip_Ntoa ip_str;
         LOGGER_ERROR(log, "cannot connect to %s:%d which is neither IPv4 nor IPv6",
                      net_ip_ntoa(&ip_port->ip, &ip_str), net_ntohs(ip_port->port));
+        *err = NET_ERR_CONNECT_INVALID_FAMILY;
         return false;
     }
 
 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
     if ((true)) {
+        *err = NET_ERR_CONNECT_OK;
         return true;
     }
 #endif /* FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION */
@@ -2060,10 +2076,12 @@ bool net_connect(const Network *ns, const Memory *mem, const Logger *log, Socket
             LOGGER_WARNING(log, "failed to connect to %s:%d: %d (%s)",
                            net_ip_ntoa(&ip_port->ip, &ip_str), net_ntohs(ip_port->port), error, net_strerror);
             net_kill_strerror(net_strerror);
+            *err = NET_ERR_CONNECT_FAILED;
             return false;
         }
     }
 
+    *err = NET_ERR_CONNECT_OK;
     return true;
 }
 
diff --git a/toxcore/network.h b/toxcore/network.h
index 34eb1f411a..40dd2dee53 100644
--- a/toxcore/network.h
+++ b/toxcore/network.h
@@ -499,13 +499,22 @@ void networking_registerhandler(Networking_Core *net, uint8_t byte, packet_handl
 non_null(1) nullable(2)
 void networking_poll(const Networking_Core *net, void *userdata);
 
+typedef enum Net_Err_Connect {
+    NET_ERR_CONNECT_OK,
+    NET_ERR_CONNECT_INVALID_FAMILY,
+    NET_ERR_CONNECT_FAILED,
+} Net_Err_Connect;
+
+const char *net_err_connect_to_string(Net_Err_Connect err);
+
 /** @brief Connect a socket to the address specified by the ip_port.
  *
- * Return true on success.
- * Return false on failure.
+ * @param[out] err Set to NET_ERR_CONNECT_OK on success, otherwise an error code.
+ *
+ * @retval true on success, false on failure.
  */
 non_null()
-bool net_connect(const Network *ns, const Memory *mem, const Logger *log, Socket sock, const IP_Port *ip_port);
+bool net_connect(const Network *ns, const Memory *mem, const Logger *log, Socket sock, const IP_Port *ip_port, Net_Err_Connect *err);
 
 /** @brief High-level getaddrinfo implementation.
  *