Remote connection via VPN - [Resolved] but ongoing discussion

I could use some help. I’ve got a Unifi Dream Machine Pro router. Roon Core (rock) is running on linux. I’ve setup my VPN on the Unifi according to @CrystalGipsy’s instructions. mDNS is on. I can connect to the VPN just fine from my Mac. I can ping the machine with my Roon server. But when I launch Roon (as a client app) on my mac, it cannot fine my Roon Core server. Any ideas on what to troubleshoot?

Any help would be appreciated!