Pihole in Docker on W10 stops working on VPN connect

I have Pihole installed in Docker on a Win10 media server (because the media server is always running anyways) and it works perfectly until I connect the media server to a VPN. With the Win10 media server connected to the VPN, no clients can connect to the Pihole and they timeout while trying to load web pages or fall back to the secondary (regular) DNS server. Normally I connect the Win10 media server to the VPN with the OpenVPN client, but I've also tried Windows L2TP native client and I get the same results.

For possible clarification, no other devices connect to a VPN except the Win10 media server. The Win10 media server connects to a VPN as a client - it is not a VPN server. The VPN connection doesn't prevent any other connections to the media server. I've never used Docker before, I used this guide to set it up Install Pi-hole on Windows 10 and live ad-free forever | Andrew Denty . I omitted step 9 because I only want certain devices using the Pihole.

Can this be fixed so I can use the Pihole while the media server is connected to the VPN, or do I have to setup Pihole in a different manner? Thanks in advance for any suggestions.