My setup:

Router: 192.168.1.1 with port forwarding to 192.168.1.3 (external 8080 because my ISP blocks 80, internal 80.)

Pi4: 192.168.1.3 with Apache running to process occasional requests from my voip provider.

I can access my apache server both via LAN 192.168.1.3 and externally via DDNS myhostname.myddns.com:8080.

However, when I turn on openvpn to my external vpn provider on Pi4, I can access my server via LAN 192.168.1.3, but I can no longer access it externally via ddns.

Is there a way to make it work?

Many thanks.