Have you tried investigating the config it produces and comparing that to what you ended up with on your failed attempts? Way back when I first started using Op

Have you tried investigating the config it produces and comparing that to what you ended up with on your failed attempts? Way back when I first started using OpenVPN installing a quick-setup in a VM was how I found a glaring mistake I'd been making (with routing, it turned out, not the OpenVPN config itself). Not that it massively matters if you are happy with PiVPN of course, but understanding more may help you diagnose issues should PiVPN ever fail.