Network capacity limits

I have a Raspberry Pi 3 with a CC2531 stick flashed with I have a long extension cable to extend the range, and the pi is located in the centre of my 2 bedroom apartment.

I have 42 devices, and I’ve apparently hit a wall where they can’t all be paired simultaneously. If I restart zigbee2mqtt whichever devices connect first stay connected, and others will never connect, even if I put them right next the coordinator and try to pair them.

Many of the devices should be capable of acting as routers, there are lights throughout the apartment that are always on. What can I do here? I have another Pi and another CC2531, should I just split the network in 2? Is there a better firmware that I don’t know about (I started on an early firmware with no device limit and that was unstable, causing crashes and the need to re-pair everything eventually).

Any advice?

You could try reflashing your stick with the ‘source-routed’ variant. Re-pairing is not necessary.

Hey @francisp,

That does sound like what I need! I’ve read through and source routing is what’s recommended for me.

The question is whether 40/40 is “40 normal routes PLUS 40 source routes”, or “40 normal and source routes”, in which case my network might be too big.

The 40/40 gets me confused too. However, on the zigbee2mqtt wiki :

I read that zigbee2mqtt has a limit of 20 devices, is this true?

Definitely not! Example given: the default Zigbee2mqtt CC2531 firmware indeed supports 20 devices connected directly to the coordinator. However, by having routers in your network the network size can be extended. Probably all AC powered devices e.g. bulbs serve as a router, you can even use another CC2530/CC2531 as a router (which has a limit of 21 devices).


When using the default Zigbee2mqtt CC2531 coordinator firmware + 2 CC2531 routers your device limit will be:

  • Coordinator: 15 - 2 routers = 13
  • Router 1: 21
  • Router 2: 21
  • Device limit of 55 devices

I currently have 3 CC2531 routers, so in theory I could expand to 75 zigbee devices.