Yeah, you do not have enough Zigbee Router devices in your Zigbee wireless mesh network!
Zigbee is not only very sentitive to EMF interference but due to poor radio propegration and low-power radios these devices uses they totally depends on mesh networking technology in order for all messages send to reach its intended target without them having to be re-sent over and over, meaning you always need many Zigbee Routers as for robustness Zigbee devices need to have multiple paths to reach the Zigbee Coordinator. Read:
Again, start by follow all these tips (including adding a few “known good” Zigbee Router devices):
You should know how Zigbee works so also recommend reading all these additional community guides: