I have your exact setup. Have you done any tweaking? What channel are you on? All I can think is, I have thick concrete walls. Changing battery also didn’t help.

I use zigbee and their sensors just keep dropping off the network

Because it takes work for them for no pay. If they get paid they will do it in an instant.

user name and/or password are wrong? Not much we can say about anything here.

You guys have backups?