This can be caused by all kinds of things.
When you did not update anything (also no auto updates!), it is possibly a changed (wifi) interference issue.
Maybe you’ll have to add an extra router device (in theory any mains powered zigbee device).
You’d check if your 2.4GHz wifi channel is on a fixed channel, and does not interfere with the used zigbee channel
Maybe a close neighbour changed their wifi.
