Windows 10: machine can't be added to Homegroup

I upgraded several workstations .. one from 8.1 and another on an HP laptop from win 7 , as well as a fresh install of win 10 on a third., all 64bit machines. After a lot of hassle I got the homegroup working on all but the machine that was on w7 earlier ... (It worked before the w10 upgrade with the homegroup).

When I try to join it, it tells me the machine can't be added. Then I run all the homegroup diags, network diags, checked services, etc. No matter what I try, the machine upgraded from w7 won't join the homegroup. There must be a way to get it working, but everything I've tried has led nowhere on this one machine.

First it tells me "You've been invited to join a HG"
click on join
indicate all the sharing options
enter the password
Then it says "Can't set up a HG this computer"

:)

 

Can't add computers to homegroup--Windows 10

I've got 4 machines here, all running Windows 10. I set up a homegroup on one of them, then started adding the homegroup password to the other three. This worked just fine with one of the computers,
but it's not working with the other two. I can see the machine names on my network so I know they're there, but I can't get them to set up the homegroup. What am I doing wrong? Any ideas? Thanks.

 

Home Group Issues in Windows 10

I have a similar problem with an important difference.

I had a homegroup with my Windows machines on 8.1, but the homegroup didn't survive the upgrade to 10. Now, all the machines on my local network are invited to join the homegroup, but none of them admits to being the owner of the homegroup. The old homegroup
password doesn't work. Consequently, I can't "delete all computers from the homegroup", and I can't "create a new one from scratch". How do I get out of this loop? I just want to start again!