Getting disconnected nearlie every game on our network?

[Zaiki]

ERROR

Game disconnected: Client closed down connection. Check your network connection and make sure that port 3659 (UDP) is open.

The error keeps announcing when i'm trying connect to a server. 

I have tried open the port through our router - but still not fixing the problem.

What can I do? 

Regards a friendly player from Denmark :-)

[Outlier212]

I did not have this problem until very recently. Nothing has changed on my system.  I entered the router and it looks like 3659 is open to me.