Just wanted to add… After reading your initial post I did some more digging on adding tracking headers, etc… especially by T-Mobile.

While it’s definitely a thing, it only applies to HTTP traffic. Even HTTPS blocks their ability to add those headers. So any traffic that’s using any other protocol (DNS, email, ssh, or just gaming, etc…) would be safe from your ISP from at least trying to add these tracking headers.

Yes but while the service is targeted for home use there still is remote work which generally requires a VPN back to the company network. They wouldn’t be able to block this. Now sure they might be more inclined to block Mullvad but they’d impact too many businesses by blocking wireguard as a whole.

And assuming they did block Mullvad but not wireguard… Just rent a VPS and install a wireguard server and client there to bridge back to Mullvad.

I know this doesn’t help much but I use T-Mobile cell towers with an always on VPN with no issue. But I don’t see why they’d block Mullvad. (I’d be more concerned that they’d block them than wireguard in general). But there’s completely legitimate reasons to use both so I don’t see them really bothering to block either.