Hi @Julian_Jakobs,
We’re sorry to hear that you’ve hit a barrier with your service provider’s implementation.
There are fruitful workarounds in #tinkering using VPNs and proxy servers. While we don’t officially support these, they’re quite reliable for using ARC on the go for users who have innavigable issues with their provider. Please see here, for example: Tailscale implementation with ARC to circumnavigate ISP CGNAT.