Just a thought here, but have you tried DD-WRT? I've been using it for around 3-4 years with BolehVPN and it's been great, also a lot simpler to deal with.
I know that DD-WRT pumps out firmware versions and documentation isn't the greatest, but I have had only a few minor issues over the years, and it's been rock solid.
I'm a pretty serious Linux Geek and I was turned off by OpenWRT and found DD-WRT to be a better solution, but of course, each to his own...