This problem has not been fixed. Most of the time Web Shield blocks the VPN, occasionally it lets it through.
Turning off Web Shield, enabling VPN, and then turning Web Shield back on, will usually allow the VPN to work. Sometimes it blocks it again after a few minutes.

This is a known, reproducible bug. Why hasn’t it been fixed? I already submitted a bug report and log.

You can’t force people to pay for your VPN by blocking the free one. That will just make you enemies.