Try power-cycle Zigbee Coordinator and then restart ZHA or reboot Home Assistant. Losing the connection to a remote network attached Zigbee Coordinator, especially WiFi-connected ones, is another reason why USB-connected Zigbee Coordinator adapters i generally recommenced over any others. See warnings:
https://www.zigbee2mqtt.io/advanced/remote-adapter/connect_to_a_remote_adapter.html
Regardless suggest that also follow this → Zigbee networks: how to guide for avoiding interference and optimize for getting better range + coverage