server problems

[Drocona]

RCon works on TCP 27015, that port needs to be forwarded if you want to use RCon on the external IP

Also sometimes RCon binds to the wrong IP on the server, setting rcon_address <ipaddresshere> in the server.cfg can help solve the problem.
RCon can also try to connect to the wrong IP on the client, type rcon_address <ipofserverhere> in the console to make sure it's correct. If your server is on your own network use the internal IP of the server, if it's in a datacenter use the external IP of the server.