WIN 10 LAN Sharing Issue

I have a network sharing issue.

I have a home LAN with several PC's. I am trying to be able to share files and folders between the PC's on the LAN.

I am unable to see other computers on my LAN in "Network" from these computers. I do see other connected devices such as printers, and Roku.

I have 2 computers specifically that I want to be able to share between. My "main" computer this one, and my shop computer. They are both on the same LAN. And all have internet connection.

All computers are running WIN 10, fully updated.

I have followed the Microsoft page for sharing help, but no joy. So now I don't know how to try to figure out how to proceed. I run Avast free AV on the shop PC, and Bitdefender on main PC. Bitdefender is in trial mode, I have been a long time user of Avast and considering options. Not sure if the AV choices are blocking my LAN use, I have disabled the Bitdefender firewall as a test. No change. Avast does not have a firewall in freeware.

Where do I begin to sort this out?

Are both computers setup to require a username/password at boot up?

Yes

Same username/password. Login to microsoft account.

Possibly useful links:

https://pureinfotech.com/setup-netwo...ng-windows-10/

https://www.isunshare.com/windows-10...indows-10.html

https://www.makeuseof.com/how-networ...re-windows-10/

https://www.tenforums.com/tutorials/...dows-10-a.html

Thank You, I'll check them out.