I work with some colleagues who use OpenVPN to connect to their SVN repository and as such have to authenticate via a VPN tunnel before I can checkout the existing codebase.
However, every single time I update Windows 10 to the latest version (which is mandatory after a while!), the OpenVPN software then fails to connect - with a brilliant and informative error "Failed to connect". Nothing in the logs, nothing in the Event Logs.
After tearing out what little hair I have left, I came across a solution on Reddit of all places - just reinstalling the OpenVPN client won't work, you have to also reinstall the TAP drivers for OpenVPN by downloading https://swupdate.openvpn.org/community/releases/tap-windows-9.21.1.exe .
Once downloaded, you have to run the TAP update script, but you MUST run it as an Administrator, else it'll fail.
Now install the OpenVPN client from your VPN address, and it should connect fine once done.