Regardless of Zigbee setup, strongly recommend read and try to follow all the tips and best practices here → Zigbee networks: how to guide for avoiding interference and optimize for getting better range + coverage
Off-topic but see related feature requests → “ZHA integration UI options to apply OTA firmware update (OTAU) per Zigbee device?” and “WTH does Home Assistant's ZHA not notify about Zigbee OTA (Over-The-Air) "update availability" and give users UI options to apply OTAU firmware updates per Zigbee device on demand?”
@Rudd-O Nice! However better if be willing to contribute improvements to both the ZHA integration documentation (should be short) as well as improve the zigpy wiki (which can be long) on the subject:
https://www.home-assistant.io/integrations/zha#ota-firmware-updates
https://github.com/zigpy/zigpy/wiki/OTA-Device-Firmware-Updates
Btw, know that it is relatively easy to edit zha.markdown via GitHub web interface and submit as a PR: