Internet is there but games keep losing connection

[EyDavid]

Hey! Without changing anything or going into any internet/router settings my connection in games started breaking.

I tested with different games so it's not a one game issue.

 

For example, in Fortnite I can run around and play the game like normal before all of a sudden the connection is lost and I'm sent back to the main menu.

The same thing happens in Discord when in a voice chat with friends, all is well and then it lags without any warning.

 

I'm connected via LAN from a WiFi extender (Speed Home Wifi - Telekom), this has not been an issue for about three years now.

What is strange to me about this is that at no point does my internet connection break. I can load websites, watch videos, etc. I even had Fortnite going in the background and as I was browsing around and the game "lost" it's connection while everything else loaded without an issue. 

 

Does anyone have an idea of what could be causing this? Maybe someone knows a diagnostic tool I can run or something? I'm really confused and it's very annoying.

Thanks in advance and please feel free to ask any questions that might help you to help me! :)