I had a Netgear WNR3500L with a OpenWRT Tomato build by Shibby (http://tomato.groov.pl/) for some month as secondary VPN network in combination with AirVPN. Sometimes the VPN disconnected and I had to connect using the OpenWRT UI, but most of the time it was ok. Also there are some good posts about router setups at the AirVPN forum, maybe you should have a look there (https://airvpn.org/forum/15-how-to/)