How to improve network range.

In case you are experiencing an unstable or bad network range you can do the following things to improve your network.

CC2531

Connect the CC2531 using an USB extension cable

The range of the CC2531 can greatly be improved when connecting it with an USB extension cable instead of directly plugging it into the computer (e.g. Raspberry Pi). When plugged directly in the computer, the CC2531 antenna suffers from interference of radio signals and electrical components of the computer. Also be sure not to position the CC2531 too close to any other radio transmitting devices (e.g. Wifi router). A USB extension cable of 50 cm is already enough to reduce the interference.

Try different orientation of the CC2531

RF connection between the CC2531 and other devices also depends on the way it is oriented in space. You might be having very poor linkquality reports and intermittent ping failures but once the CC2531 is rotated a little it all can change greatly without re-locating the coordinator far away. Try to experiment with positioning and orienting the CC2531 in space while controlling the linkquality values reported. You might find it useful to buy a small rotating USB connector. Like this:

rotating USB connector

Reduce Wifi interference by changing the Zigbee channel

NOTE: Changing the Zigbee channel requires repairing of all your devices!

As Wifi and Zigbee both operate on the same frequency space (2.4 GHz); they can interfere with each other. By using the correct Zigbee channel interference with Wifi can (partly) be avoided. There is a good article available explaining this: https://www.metageek.com/training/resources/zigbee-wifi-coexistence.html

To change the Zigbee channel Zigbee2mqtt uses you have to set the channel in configuration.yaml.

Adding more routers to your network

In a Zigbee network, each router will extend the range of the network (read more about this). Almost all AC powered devices will serve as a router. In case you are searching for a powerful router, the CC2530 is recommended.