I have already downgraded to 4.7.7 and completely reset the router. OpenVPN is working on it now. I also tried on a recent 4.8.3 snapshot and the VPN issue persisted. If I remember correctly, internet traffic was blocked but VPN traffic was allowed thru on 4.8.2 and 4.8.3
If possible, please try upgrading your router to the latest snapshot, and share your router with us via GoodCloud, I would like to remote check this issue in your router.
Please PM me your router MAC address and the Admin Panel password.
I just upgraded to 4.8.3 (release, not beta) and now I can reach both the internet and our private VPC, so it looks like the problem is solved! Thanks!