Hi Chris - personally, I have had the worst “disconnecting” issues with Xiaomi/Aqara devices and have put this down to three things:
a) Aqara devices don’t appear to follow ZigBee 3 standards fully (lots of stuff on the net about this). I worked around this (partially) by lots of debugging and upating of .webthings/addons/zigbee-adapter/lib/zb-xiaomi.js
b) battery issues - many sensors only have battery power, once the battery drains, the devices disconnect and reconnect - until they eventually die
c) Zigbee and Wi-Fi channel interfernce (and even Zigbee-Zigbee channel interference - I had two WT gateways in the same room). There is a separate articel on the forum about this topic, but since I moved by secondary gateway to channel 25 (avoid 26 with Ziaomi), all is good - on both gateways.
Hope that helps.