I used for some time a TS3 server to speak with friends on a local network without problems.

Now, a friend of mine is trying to connect to my server through internet. He uses my external ip adress (most of the time my dyndns but we checked if there wasn't a problem with it) and can't connect.

I opened the 9987, 10011 and 30033 ports. Connection failed.
I tried with a 9986-9988 range. Not better.

My firewall was switched off.

I tried this website's test (http://www.canyouseeme.org/ ) but it didn't worked (told me there was a timeout). I tried on other ports (like the ones I use for my FTP server which works) and still gave me a timeout.

The friend is able to connect to other servers (like the one given in some topics).
I am able to connect to my server in localhost and using the 192.168.x.x adress.

I don't know what to try now.

Can someone help me ?