Socket connection problems over internet

First that comes to my mind is: is there a firewall between the server and the clients when you see the problem (if this is P2P -- between the peers)?

So, check up your firewall settings -- first of all, it can be a combination of protocol and port number.

Google[^]

First result:
TCP/IP Chat Application Using C#[^]

You spent more time formulating your question, then it took me finding the answer using google.

When you want help with code you are working on, it is usually a good idea to include the problematic section with your question. Then there is an actual chance of receiving the help you need.

@Manfred : That’s why I amended it – your linguistic skills turned it into something more sensible. The code for the article works. If that program works and his doesn’t – he can take a look at the article and maybe it will help him solve his problems. If both fail that will be a fair indication that his problem is not related to his code, it may then be, as SAKryukov points out, network related. (Suddenly I couldn't post comments)

Regards
Espen Harlinn