We have the same problem here, and have tested across 3 Xbox One consoles. One console (my 'home' console) repeatedly could not connect to realms when either my wife (with Gold) tried Minecraft or my daughter tried (using my 'home' Gold account). We could all login to realms on other devices (iPad, Android) so it seems to be an Xbox One specific bug.
Try going into settings and 'reset' the xbox whilst keeping your games installed. You will need to add your user account again but the downloaded games stay on the drive. After doing this we've been able to successfully connect with the problem Xbox One so far - but have no idea what this reset has achieved - perhaps that will shed some light for the developers though!
Tim Cowles
We have the same problem here, and have tested across 3 Xbox One consoles. One console (my 'home' console) repeatedly could not connect to realms when either my wife (with Gold) tried Minecraft or my daughter tried (using my 'home' Gold account). We could all login to realms on other devices (iPad, Android) so it seems to be an Xbox One specific bug.
Try going into settings and 'reset' the xbox whilst keeping your games installed. You will need to add your user account again but the downloaded games stay on the drive. After doing this we've been able to successfully connect with the problem Xbox One so far - but have no idea what this reset has achieved - perhaps that will shed some light for the developers though!