Problems signing into my son's account

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 Ryan

In order to isolate the issue a bit more, where is your trying to sign in with his account?
On Xbox, PC or Mobile?
Is this happening with an specific game or with all the games?
And, are you (or him) able to sign in properly here?
https://account.microsoft.com/profile

Does it matter who installs the game? Me, my oldest son, and my youngest son all have different accounts but we belong to the same family account.

My oldest son uses the Home console and signs into that console with his own account. My youngest son has his own console and signs into that console with a different account. If my oldest son installs the game on the Home console will my youngest son be
able to see the game on his own console while signed in with his account? Or does my oldest son have to sign on to both consoles?

I have the same problem. I can sign into the Xbox one but my son can't, even though I can sign in here with his account.

If you followed my post your son would have "admin or parent" rights on your One. If that is not a problem Sign in with his has the primary account. Create your account (free) and sign in with it on your One. Have your son add you as family on the One. No
need to buy a second Gold if you have no aversion to my first sentence.

When I sign into Xbox live with my account after my son signs in, all I get is an error message that there is a temporary problem with the server and to try again later.

Can someone please fix this.