It’s the last paragraph that resolved this for me - plugging an Ethernet cable from the Synology into the back of my Eero mesh network. I had totally forgotten about that ability as it then looks to the router like another connection to the network and it assigns an IP address. Back in WIsconsin, my house was wired for Ethernet and my switch plugged both into that network, and the Eero’s were also backend plugged into the network as well.
In Vermont, I don’t have the Ethernet backbone.
And, the Eero is in my office along with the Mac and the Synology, all my static IP addresses and all that are now all back in play and I successfully connected to the Synology.