VPN Issues with M6 Hotspot using AT&T Cellular?

Today I started having trouble connecting from mac to my Synology NAS through OpenVPN via my M6 Pro hotspot.

During my troubleshooting to figure out what the problem is, I discovered that if I have an active Nord VPN connection on my mac, I can then use OpenVPN to connect to my Synology NAS at home and join my home network.  If I am disconnected form Nord VPN, OpenVPN won't establish an connection to my home.

I'm not sure what's going on here.  I'm starting to suspect that AT&T cellular is somehow blocking my ability to establish an OpenVPN connection to my home.  Has anybody out there had a similar experience?

Thank you,