Bedrock realms server, unable to access realms. "error - You cannot play online multiplayer through Xbox Live because of how your account is set up"

Can't access realms at all (realms is the only reason my group still plays Minecraft, love the work you're doing, but without multiplayer it's just not worth it).

Whenever I go to the app on the Xbox one to open my account, it says:

"error - You cannot play online multiplayer through Xbox Live because of how your account is set up. This can be changed in your privacy & online safety settings on xbox.com".

I have followed the link and have changed the required settings multiple times, I'm not a child, I don't have a child account, I'm 27. But for some reason it still wants me to change settings, that are already changed as directed.

I can't get on to realms at all. This has been a long term issue, to the point where I haven't accessed the realm I'm paying for for 1.5 months!!

Please sort this, I'm in isolation and really bored!