See https://www.home-assistant.io/integrations/zha#defining-zigbee-channel-to-use
Do not confuse Zigbee channel numbering with Wi-Fi channel numbering.
https://support.metageek.com/hc/en-us/articles/203845040-ZigBee-and-WiFi-Coexistence
More important though is to read and follow this → Guide for Zigbee interference avoidance and network range/coverage optimization