I was using both a VPN (Private Internet Access) and Ubuntu WSL1 on Windows 10 with no problem.
Then I upgraded to WSL2 Ubuntu 20.04. I found that WSL 2 broke my file reloading, so I downgraded the version back to WSL1. I also installed the latest version of my VPN in that time. (I also installed the latest version of VirtualBox (6.1.34), found it didn't work, so I reinstalled version 6.1.3.)
Now WSL1 Ubuntu cannot connect to the Internet when my VPN is enabled. What files and settings must I check to fix this please?