diff --git a/artiq/frontend/artiq_devtool.py b/artiq/frontend/artiq_devtool.py
index a602cdd71..8324b8aa6 100755
--- a/artiq/frontend/artiq_devtool.py
+++ b/artiq/frontend/artiq_devtool.py
@@ -112,11 +112,31 @@ def main():
 
         elif action == "connect":
             transport = client.get_transport()
-            def forwarder(port):
+
+            def forwarder(local_stream, remote_stream):
+                try:
+                    while True:
+                        r, _, _ = select.select([local_stream, remote_stream], [], [])
+                        if local_stream in r:
+                            data = local_stream.recv(65535)
+                            if data == b"":
+                                break
+                            remote_stream.sendall(data)
+                        if remote_stream in r:
+                            data = remote_stream.recv(65535)
+                            if data == b"":
+                                break
+                            local_stream.sendall(data)
+                except Exception as err:
+                    logger.error("Cannot forward on port %s: %s", port, repr(err))
+                local_stream.close()
+                remote_stream.close()
+
+            def listener(port):
                 listener = socket.socket()
                 listener.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
                 listener.bind(('localhost', port))
-                listener.listen(1)
+                listener.listen(8)
                 while True:
                     local_stream, peer_addr = listener.accept()
                     logger.info("Accepting %s:%s and opening SSH channel to %s:%s",
@@ -128,31 +148,17 @@ def main():
                     try:
                         remote_stream = \
                             transport.open_channel('direct-tcpip', (args.device, port), peer_addr)
-                    except Exception as e:
+                    except Exception:
                         logger.exception("Cannot open channel on port %s", port)
                         continue
-                    while True:
-                        try:
-                            r, _, _ = select.select([local_stream, remote_stream], [], [])
-                            if local_stream in r:
-                                data = local_stream.recv(65535)
-                                if data == b"":
-                                    break
-                                remote_stream.sendall(data)
-                            if remote_stream in r:
-                                data = remote_stream.recv(65535)
-                                if data == b"":
-                                    break
-                                local_stream.sendall(data)
-                        except Exception as e:
-                            logger.exception("Forward error on port %s", port)
-                            break
-                    local_stream.close()
-                    remote_stream.close()
+
+                    thread = threading.Thread(target=forwarder, args=(local_stream, remote_stream),
+                                              name="forward-{}".format(port), daemon=True)
+                    thread.start()
 
             for port in (1380, 1381, 1382, 1383):
-                thread = threading.Thread(target=forwarder, args=(port,),
-                                          name="port-{}".format(port), daemon=True)
+                thread = threading.Thread(target=listener, args=(port,),
+                                          name="listen-{}".format(port), daemon=True)
                 thread.start()
 
             logger.info("Connecting to device")