Try to ping the server and see if the connection request times out. Type ping laanx.fragnetics.com into your Windows Run command.
Sometimes, there can be a problem in the connection between your ISP and the server, which is harder to solve than changing firewall settings. I think I'm currently experiencing this issue - the server is up but I haven't been able to reach it for at least a week (luckily I have no real need to, myself).
Thus: if your firewall/router settings are definitely set to allow PlaneShift and UDP port 7777, but the connection is still failing, you may have to contact your ISP.