Synch Problem

I have 3 Arylics, 2 x S50’s and 1 x S10
Since the new app, I cannot synchronize one of the S50’s. They could prior to the new app. Have performed multiple factory resets, turned off all units, multiple times, with no success. They are all on the same wifi, and I can see the device on the list. When I tick the box to synchronize, the app thinks for a while, then nothing happens.
The S10 and S50 that do synch have a firmware version 4.6.328252.28 with a build date of 20210903
The S50 that does not synch has a firmware version 4.2.9326.27 with a build date of 20210226
I suspect that might be the problem, but don’t know for sure.
What do I need to do to fix it?

Yes, the latest firmware used the newer version multiroom library, and which is not compatible with the old one. The S50 device will receive update soon, have fixed the server settings.

Fantastic, works well now after the upgrade.