yazzie
I've encountered some issues with my custom OpenVPN implementation for Windows when the client is installed on a system that had previously been installed with 3rd party VPNs. In some cases not all traffic is tunnelled through the VPN and in other cases it doesn't appear that any traffic is tunnelled.
For example:
Hotspot Shield does not appear to tunnel HTTPS traffic. This appears to be implemented by a driver that it installs called the "Hotspot Shield Routing Driver 6". When my VPN client is subsequently installed, it too will not tunnel HTTPS traffic. Even after HSS is deleted, the driver that splits traffic persists and must be disabled manually through the adapter settings.
PandaPOW - A paid VPN which has also been reported to have caused issues is a paid service called PandaPOW which is built on top of OpenVPN and appears to cause issues with other installations of OpenVPN. It doesn't appear that any traffic is tunnelled through these subsequent installations that we've observed. Their site recommends deleting a folder of settings "C:\Users\[username]\AppData\Local\doEnter_Ltd". Once this is deleted and OpenVPN Community is uninstalled and reinstalled, other OpenVPN-based VPNs tested begin functioning as normal.
Has anyone else encountered these issues (or similar) in the past?