I'm trying to use a VPN to play iPad to iPad Wifi (Local) games over the internet.

Normally you open the game on both iPad's, connect to the same Wifi point and they can "see" and speak to each other.

I figure using a VPN I can put them both on the same network (either both on the VPN or one on the "real" network and one on the VPN).

On my router I've set up PPTP VPN with the ip range 192.168.1.2-50, where the PC's on the real local network are assigned 192.168.1.100+

When I connect one of the iPads to the VPN, using an external WiFi network (BT Openzone) I can ping it as expected (from any machine on the local network). However the iPad's cannot "see" each other and none of the Wifi->Wifi games work.

I've also tried connecting both iPad's to the same VPN, with the result the same. All machines on the local network (and those on the VPN) can ping the iPad's but none of the Wifi to Wifi games work.

I've set both iPads to send all trafic over the VPN and if I check their external IP's they match that of the real network.

Does anyone know how to fix this? And/or what is causing it? Or what further debug information I can provide?

Note: I don't feel this is iPad specific so would prefer if this isn't moved to a Apple SuperUser equivalent