Well that might be your problem! Don’t place Zigbee radios close to WiFi access-point! Highly recommend that you read and try to follow the tips in this guide (which including not placing Zigbee devices close to Wi-Fi APs/routers/devices) → Zigbee networks: how to guide for avoiding interference and optimize for getting better range + coverage
WiFi radios are high-energy and will drown our low-energy radios like Zigbee. So always need to place Zigbee devices a little away, regardless of which channels are used, just due to general EMF/EMI/RMI.
Also check that WiFi freqency used do not overlap with Zigbee → https://support.metageek.com/hc/en-us/articles/203845040-ZigBee-and-WiFi-Coexistence