I have been able to setup folder sharing on my Mi-Fi home network. Internet works on all devices connected. I want to be able to share between all four of my Windows laptops. Two on W 7 and two on W 10. Other devices including my wife's laptops do not require sharing facilities.

Over a few years, I added shared folders as required; often with difficulty, but eventually getting there!

I've just bought a secondhand refurbished laptop with a new clean installation by the dealer. The username was set as 'user' (can't remember the case of the letters.), however 'C:\Users\User' has first letter in caps. I get the impression that the username for networking is related to this folder's name rather than the name of the user account, which I changed.

On the two W 7 laptops, this new laptop is not visible in their 'Network' folders, but is visible on the other W 10 laptop.

However on this other laptop, when I click on the new laptop's name, I am asked to enter the network credentials for the new laptop. It would not accept the username for the laptop, but after many attempts with various values accepted the user folder name with the username's password. I solved this while typing this posting.

But getting the new laptop visible on the two W 7 laptops has so far defeated me.

Any suggestions, please?