“Unable to save changes, we are unable to connect to this service at the moment”, when...

Both of their accounts are child accounts.

I gave your suggestion a try and it WAS successful!

I changed his age to 18 & removed him from the family. It then allowed me to set a home console under that gamer tag. After that worked I changed his age back to the proper age and brought him back into the family group. Everything is now working properly as it should be!

Thank you so much! I greatly appreciate your time & guidance in bringing this issue to a successful resolution!

Is the account that you want to use as home Xbox a child account?

This can be a bit odd but:
If yes, can you try temporarily change the birth year and make it +18
Then remove and re-add the account as a family organizer using the link below:
https://account.microsoft.com/family/home

After that remove and re-add the account in the console and try again

Thanks for sharing the resolution!

I'm glad to hear that home Xbox is finally selected for the desired account

Take care!

Hi and thanks for reaching Microsoft Xbox gamer's community. My name is Josef.
I'm an Independent Advisor and a Microsoft Xbox user like you.

Hope you're doing great today despite this Smb_00

Sorry to hear that, may I know if the Xbox console is up to date?

If yes, I can advise you another 3 things to try:

1. If you didn't try it, share mobile data via wifi hotspot and connect your console in that way temporarily and try setting the console as home Xbox

2. Clear your alternative MAC address
Select Settings > Network > Advanced Settings > Alternate MAC Address
Select Clear, restart your console and give it a new try

3. In case you didn't try it, could be nice perform an offline update for your console. In that way Xbox system will be installed from scratch.
For this you need a USB and PC to format it and transfer files provided in the link below (with steps):

https://support.xbox.com/help/hardware-network/...

@JoseF

Thank you for your reply & suggestions.

- I connected through a hotspot and tried to set as home as you suggested. (Fail)

- I then reset the alternate MAC address again as suggested. (Fail)

- I checked to verify and the console is up to date.

- I performed an offline update provided through your link. (Fail)

- I also accessed developer settings in console info and reset home console. (Fail)

As stands I am still unable to designate a home Xbox via that specific gamer tag.

BTW, I have attempted designating a home console with that gamer tag on four (4) different consoles, all of which I receive the same message. I do not have this issue with any other gamer tags. This in addition to all the failed fixes leads me to believe that it is NOT likely to be hardware or software related. It seems to me that there is some issue with that specific gamer tag that needs resolved. Is there anything we can look into gamer tag wise that may help resolve this issue?