Trusted Devices and Family Information not showing

I appreciate the thought, but Apple has no problem saying what ports are required for things like BacktoMac, AirPlay, and Bonjour so it seems exceedingly unlikely that there is some secret sauce here that they won’t share.

In addition, I tried on a different network that has no firewall and it didn’t work.

After many reboots and network resets it seems to be working. Seems to me that rather than secret sauce, there are some fragile pieces. I can’t prove it, but it seems like you have to add your iPhone to iCloud before your iPad or things might not work. Jut an example.

Thanks, unfortunately without knowing what ports are required or whatever, that doesn't help much.