This question may have been posted already. I'm sorry if it's the case, but my english isn't that good, and it's hard for me to fast-read topics looking for something related to my problem.

I have a TS3 server installed on a stable debian server. The TS3 server works pretty well. I've been using it the whole last year without any problem, and my friends are still using it without problem.

But now, my client isn't connecting anymore :
<20:52:30> Trying to resolve hostname <hostname>
<20:52:31> Trying to connect to server on <hostname>
<20:52:36> Failed to connect to server
This is not a client issue, but a firewall issue. But I'm on a student internet connection, and I can't change this.

I would like to know if it's possible to use different ports server side. For now, my server is using default ports :
[email protected]<hostname>:~# netstat -tulanp | grep ts
tcp        0      0 *               LISTEN      4900/ts3server_linu
tcp        0      0 *               LISTEN      4900/ts3server_linu
udp        0      0 <ip>:59078       ESTABLISHED 4900/ts3server_linu
udp        0      0  *                           4900/ts3server_linu
I don't want to change this, but I could add an iptables rule for this.

Would that be possible without creating problems for the server ?
Are there canonical ports for this ?
Do I have forgotten something ?

Thanks a lot for your help.