UPNP server

Wifi router or Windows computer with activated Internet connection sharing can send announcements through UPNP, that they provide Internet gateway connectivity. This causes network problems on other Windows computers with activated UPNP client service discovery. Due to this all users with an active UPNP WAN gateway will be locked.

The problem can be fixed by disabling the UPNP server. Instructions can be found under the following links:

When using a wifi router, please consult the manual on how to disable the UPNP server.

After resolution of the cause unlock the network socket.