Ever heard the saying “you get what you pay for”? As yes Zigbee devices have really bad radio propagation and is extremely sensitive to interference so you need to both add loads of known good Zigbee Router products and take actions to avoid sources of EMI/RMI/EMI as well as making sure there is no overlapping Wi-Fi channels. Read and follow this → 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
Z-Wave have much better radio propagation and longer range because it uses Sub-1GHz frequency, but you still want to avoid having Wi-Fi or other possible sources of EMI/RMI/EMI too close to the Z-Wave Controller and devices as it is still possible to jam the signal causing wierd symptoms like quirk battery drain. And you still also want to add many Z-Wave Repeater devices, (especially if you live in Europe where Z-Wave signals are not allowed to be as strong).