Screen Sharing fails after connecting

I'm having an issue with Screen Sharing maintaining a connection to my Mother's computer but I am able to connect without any issues to my Father's computer. Both parents are now using new MacMini's with the latest version of Ventura. I'm using Big Sur (11.7.9) on an old MacBookPro. I connect to my Mom's computer for about 1-2 seconds, see her screen, but then the connection fails and I get this warning:

"Connection failed to 'Mom'". Unable to communicate with 'Mom'. Make sure the remote computer is available and the firewall is not blocking screen sharing. <OK>

When I was setting up their new Mini's in their home, I was able to connect to my Dad's computer while on his network. I am also able to connect to Dad's computer from my house in another state. He could also connect to me and to my Mom's computer with his new system. However, whenever I tried to connect to my Mom's computer, I would see her screen for a second or so and then the connection would fail and I would get the above warning. Same when she tries to invite me to share her screen.

Today, I was able to connect to my Dad's computer from my house. I was then able to control his computer and use his computer to connect to my Mom's computer (both on the same network in their house.) So I was able to control my Dad's computer and, through his computer, also see and control my Mom's computer. This is a poor work around.

Why would my computer work two ways screen sharing with my Dad's, his computer work two ways screen sharing with my Mom's computer, but the screen sharing between my computer and my Mother's computer fails after 1-2 seconds?

Being able to help my Mom with her computer by screen sharing saves me a 4.5-5 hour drive up to their house each week or two (as much as I like to see them!)

I've already tried reloading Mom's OS.