It seems that I cannot access my ts3 server from another ip as serveradmin.
On the computer that I used to originally install the server, I can access it.
This might be a stupid request and I apologize for this, but it is the first time creating a TS3 server.
Needed *Query port is not forwarded in router / firewall.
Thank you, I have just added all of them, missed a few.
I will let you know a little later when I will test from another computer.
Here it is how they look like. I forgot to mention that this is a linux server hosted on an ubuntu machine.