Joining the with same IP because of LAN not possibly?!

[General_Dicht]

Greetings everyone!
I´m pretty new to this mod and I already have a Problem.
A friend of mine and me are at my house and we want to play Discovery both online at the official (most used) Server. Yesterday, and a few times before, this was no Problem, but today only one at a time can join.
The other one gets an message, regarding maybe the connection is broken. But its all fine and we can both join... but like I said, not at the same time.

My Gamename is "General_Dicht" and the one of my mate is "Beef_Supreme".

Is this any kind of protection from the server? Is there any way to solve this problem? We were really looking forward to an fun weekend =(