IPhone PPTP VPN – GRE Protocol Issues | it-fabrik blog. Argh. That's exactly where my experiments failed - the VPN doesn't work over Edge - and it's probably because Telekom filters GRE (verified via a WLAN connection and then everything works fine). Why do these stupid mobile providers mess around in the network, they should just provide a connection and that's it. Now I have to manually turn on the VPN in WLAN environments that I don't trust, just because the Telekom people think I shouldn't be able to establish VPN connections over their sacred network. You're supposed to be able to do this via another APN that assigns public IPs and doesn't have a NAT box in between, but whether it's then billed as a flat rate with the tariff, of course, no one can say. I hate mobile providers and their protectionist behavior and their chaotic network structure.