Galaxy S10 cannot find server

[costero]

I've got Mezzmo running on my Win10 PC, with a Samsung series 8 TV; that part works fine.

I have Mezzmo Android running on my Samsung S5e tablet; that part works fine; from my tablet, I can see (and run files from) the server on my PC.

I've installed Mezzmo Android on my Samsung Galaxy S10 phone, and that install cannot find the server on the PC.
I have uninstalled and reinstalled multiple times, I've checked the device list on my PC, new connections allowed, etc. etc. -- everything is as spec'd in the FAQs I've read.

But I cannot get the !@#$%^&! phone to see the Mezzmo server on the PC. (It does show the phone's local Mezzmo server, which I don't care about.)

Any ideas?

PS: All Media Devices shown on my PC's Mezzmo have the same IP numbers: 192.168.0.xxx