I wanted to create a Minecraft server and so that my friends can play on the server, I have to open port 25565 and my question now is how I do it. I'm at Unitymedia.
As far as I know, Unitymedia works with DS Lite or CG NAT. This means that you share the public IP address with others. Port sharing for IPv4 is therefore ineffective. You have to do it for IPv6 and the server can only be reached via IPv6. How to do port sharing is in the router's manual.
If you still have a Unitymedia box, you may be lucky and still have this function, but if you have the Connect Box from Vodafone you can unfortunately forget it. (Vodafon bought Unitymedia.)
Here is a tutorial if you still have the Unitymedia box:
There you just have to release port 25565.
