Zigbee repeater best job cheapest price

[Ken_Fraleigh]

Cheap contact sensor

So just get this add them and put them around the house? https://www.amazon.co.uk/Sonoff-Universal-Gateway-Antenna-Assistant/dp/B09KZX4WSB/ref=pd_lpo_2?pd_rd_i=B09KZX4WSB&psc=1 What firmware do I need?