After years of mucking around, I have finally found a solution, courtesy of another member, over on this associated thread:

Folder/Drive sharing fubarred after 1803 upgrade... - Windows 10 Forums...

Thanks for the info guys - some progress has been made... The laptop can now see both of the desktop PCs and can access the shares without being prompted for Network credentials, although strangely...

Hi Guys,

This issues has been driving me nuts since the 1703 Creators Update. I've searched the web and tried pretty much everything to fix it with no luck.

So I let it slide until now. I've...