I unchecked the "Automatically sync when this phone is connected" option, and now the message no longer appears. I'd noticed that when the message came up, it was attempting to sync, and was on step 3 of 4 - determining tracks to sync. Perhaps once upon a time, I had my iTunes library on the network share, so it was attempting to sync from that? ...
Spent all day on this. All credit goes to @mike-petrichenko, wouldn't have been able to do this without him providing the solution.
For a computer with 2 WIFI adapters/NICs, these instructions will allow you to use:
1 WIFI Adapter/NIC to connected to a Router/Internet.
1 WIFI Adapter/NIC to Host a Windows 10 Mobile Hotspot.
Decide which WIFI NIC you wish to ...
In the guide you link to, the “server” side is restricted to the following cipher suites:
This isn’t bad, but it can prevent ...