I can’t comment on an upgrade restoring the backup from 2019 model. Not sure if that could cause issues or not but mine is stable with the original power supply on Wifi. For couple of days, I had issue, and I unplugged it from power for more than 15 minutes and repluged it and I have no disconnection anymore.
As far as I know, only the first couple of batches of Homey 2023 had a bad power supply so if this is a brand new one it should not be an issue. I’m using the power adapter that was provided by Homey without problem.
Since Zigbee network can interfere with Wifi, I would try not to put them too close to each other.
I would also manually set the channels for all the different Zigbee and Wifi networks, so they don’t interfere with each other. Did you add Zigbee routers first?
I would post this under the respective thread: [App][Pro] HomeKitty 
(aka HomeyKit 3.0) - Apps - Homey Community Forum
