I have made a online player game in which i use TCP connection between server and client, and UDP (DatagramSocket) between clients (its a real time game).
My problem is that i can play with some friends but no with others, that is to say, my UDP connection works only with some PCs. I think the only possible reason for this is that their ISP or Firewall is blocking the UDP port.
Is there any solution to make it works for all without adding a rule manually?
Thanks in advance
Firewalls and ISP could be the problem but its most likely port-forwarding not setup correctly. Try to look into UPnP (Plug and Play) for games.
But, for PCs that got port problems, try to use: Port Checker tool