Zigbee devices 0 LQI

Hello there

I have many Zigbee connection problems. The main problem are my devices outside. The are 3 Lamps and 2 contact sensor. They often aren’t reachable and in Z2M there often is a LQI of 0.
Because of that I bought a cc2531 and flashed it as a router and aimed the antenna directly at the lamps and contact sensors. Between them there is a window and about 10m. As you can see in the pictures, there are routes to the Gartenlaterne 1-3 which aren’t 0 LQI but it is shown as 0 LQi in Z2M.
Can you help me?

@COUBOT - Please clarify what you mean by

What antenna does the coordinator have? Depending on the antenna and how you ‘aimed’ it, it may even have made things worse. Also, did you check whether those devices are now routing through the new router? I’ve read many times that some devices don’t always change their routers once set (even though I thought they would, and makes little sense that they don’t… but this issue may be limited to specific hw). Placing the router in between the devices and the coordinator and then using the “Add devices via this device” found in the options of the new router you added (this is on ZHA, not sure about Zigbe2MQTT which I am guessing is what you are using) may help ensure they route through the new router.

I have the SONOFF Zigbee 3.0 USB Dongle Plus as the coordinator and the cc2531 with antenna as repeater aimed at the lamps. After setting up the repeater I reconnected the lamps to get the strongest connection.


The weird thing is, in the upper pictures are routes to the lamps which have enough LQI.

In this picture you can see that the coordinator has no connection to the lamps and the contact sensors. But the repeater(Verstärker Küche) between these devices has enough LQI.

In Z2M it is shown as:

@COUBOT While this is likely NOT the issue, pointing that omnidirectional antenna correctly means putting it upright (vertically) as the lobes are on the sides. If by pointing it you mean putting it horizontally so that the tip is in the direction of the bulbs, you are actually offering the lowest gain part of the antenna to the devices.

After adding the router, have you removed the bulbs and added them back in their normal locations? Also, I’ve found that sometimes it takes a while for the mesh to settle down and start working as expected after changes are made.

On another note, most of the mesh appears to be light bulbs and I have often read about how bad they are as repeaters. The reasons discussed were poor design, and the fact bulbs can be powered off at the wall thus “damaging” the mesh. I don’t use zigbee bulbs as I opted for in wall zwave switches and dimmers instead. The ~21 RGB lights I have that don’t work on dimmers are all LIFX therefore WIFI and are in lamps that are not on a switch (as a rule I don’t like putting smart devices behind a manual switch). You might see a benefit in adding a few wired routers that never get turned off if you can. As mentioned above, you might find that the bulbs will work fine if you let them be overnight (mesh self healing?). I believe a trick to force the heal is to power down the coordinator for 15 minutes and all the nodes will panic and start searching for a new route.

I have the same coordinator and while most devices can reach it directly, they show up with poor LQIs (non green lines) on the map:

I have a lot of always on routers uniformly spread across the house. The mesh is mostly stable except some older sensors that love to drop off.

Be sure to try adding your bulbs using Z2M’s equivalent of this:

Use this option in the router you want the bulbs to use. While this may change later on, it might get it started on the right path.

Thank you for your detailed response.

Here is a picture of the repeater aimed at the lights and the contactsensors behind the light.

Yeah, I completly removed the lamps and contact sensors and connected them again.

The next thing I’ll try is to put the antenna into a vertical position, change the Zigbee channel from 15 to 25 and update the firmware of the stick, as you suggested in the other post.

Maybe it will fix itself over night. Let’s see.

The window frame is aluminium, have you tried to prop it up so there is just glass in between? It should still work even if you don’t but given the issues tou are having it is worth a try.

Yeah I propped it up and put the antenna into a vertical position. Over night they completly lost the connection…

Do you know if devices require to have a route to the coordinator or can they just be connected with routers? Because in this picture every device is connected directly to the coordinator and to other routers. If the route to the coordinator looses connection the device goes offline wether there are other better routes from other routers to the device or not.

@COUBOT The whole point of a mesh network is that devices do not need a direct connection to the coordinator as they can hop through other routers. However the fewer the hops the better the performance. Also, there is a limit on how many devices can connect directly to the coordinator that depends on the chip / memory of the coordinator and the firmware. I updated my sonoff coordinator to a recent beta version of the firmware and my direct connections went from 23 or so to over 40. Performance seems faster and more reliable. Many of your routers are bulbs… is power 100% of the time always on? Or, does your family turn them off at the wall switch? The latter can cause a mess on your network as you keep breaking it by taking down routers.