Zigbee range and how to improve

@Peter_West Again I collected a lot of specific details on the two models in those other linked threads:

https://community.home-assistant.io/t/iteads-sonoff-zigbee-3-0-usb-dongle-plus-model-zbdongle-p-based-on-texas-instruments-cc2652p-20dbm-radio-mcu-now-sold-for-19-99/340705

https://community.home-assistant.io/t/itead-s-sonoff-zigbee-3-0-usb-dongle-plus-v2-model-zbdongle-e-based-on-silicon-labs-efr32mg21-20dbm-radio-mcu-now-sold-for-19-99/442695/