Zigbee Router devices are extremly important for your Zigbee network mesh to work so your need to sort that that ASAP or your batteries will drain very quickly. Read and follow these best practice tips-> Zigbee networks: how to guide for avoiding interference and optimize for getting better range + coverage
Note that many Aqara and Xiaomi devices have buggy firmware that lock to device they are first paired to which means that you need to re-pair them if you later add Zigbee Router devices as they will not automatically move to better Zigbee Router devices. See → Not many people know that... A random collection of Zigbee trivia