Frustrating Lan Problem

I'm sure the answer to this is staring me in the face, but I'm not seeing it. My LAN consists of three computers and a NAS and uses HomeGroup to configure everything. Fixed IP addressing is used in all devices, assigned by the router. It has been problem free for years and has been untroubled by two of the computers, including this laptop, upgrading to Win 10 from Win 7 but as of yesterday my Win 10 laptop can no longer access the 'main' PC, \\BJB-NEWPC -



- The laptop can access everything on the network apart from \\BJB-NEWPC
- \\BJB-NEWPC can see the whole network
- The third PC on the LAN can also see the whole network
- Teamviewer can access \\BJB-NEWPC from the laptop over the LAN
- \\BJB-NEWPC's IP is not blocked in Hosts on the laptop
- The laptop also has a Win 8.1 system on it using the same fixed IP as Win 10. That can access the whole network too

I'm stumped.

 

Bit more clarification, the media player connection works so it's just file and printer sharing on this one branch of the LAN that isn't working.

 

Sort of obscure problem you could spend days on and still not resolve, so I summoned Acronis to the rescue and restored an image of the laptop from June 2. All OK now and it will be interesting to see if it recurs as the June updates get installed.

 

[QUOTE="Earthling, post: 1961121, member: 147604"it will be interesting to see if it recurs as the June updates get installed.[/QUOTE]
It didn't recur, which leaves me wondering what did cause it? The only thing I had done that I do not usually do is run WiseCare365 cleaning functions but that is no more than a slight suspicion.