Network heal is only for Zwave. Zigbee doesn’t have such a concept unless you physically unpair and re-pair the devices. However, for your kitchen light example, you could try to unpair it, then go on the device page of your washing machine and select the “Add devices via this device” in the 3 dots menu next to Reconfigure:
I’m guessing this means there’s a wifi access point right on top of it, right?
If so, the best way to deal with this is to plug your skyconnect into a USB2 extension cable to avoid interference from both the wifi as well as the server itself.
More details about this here Zigbee network optimization: a how-to guide for avoiding radio frequency interference + adding Zigbee Router devices (repeaters/extenders) to get a stable Zigbee network mesh with best possible range and coverage by fully utilizing Zigbee mesh networking