No internet connection using MullvadVPN (Wireguard) on Ubuntu

I am using my local Wifi, everything normal. Using Ubuntu and the .deb Version of MullvadVPN. Flatpak, .deb, Snap apps all work normal.

Mullvad settings:

  • Wireguard
  • IPv6 allowed
  • DNS blockers (trackers, gambling, ads, malware)
  • Killswitch
  • Wireguard port set to automatic
  • IPv4 vs. IPv6 automatic (both 2 settings dont change anything)

with the VPN off everything works normally.

I guess its a Ubuntu port problem again, but cant find a solution. I use the Flatpak version of the Brave Browser.

Thanks in advance!