Interesting Zigbee ZLL behaviour


Thought I’d share some interesting findings as part of my ongoing investigations in my intermittent sticking of zigbee devices in my home. @vlad has been doing some great investigative work and has provided me with some routing information occuring in my zigbee mesh.

Here’s an earlier snapshot I’ve translated into names of some of my devices. What is very interesting is the fact that a number of the devices like “Lounge Window Light”, “Kitchen Bar Light” are actually Osram ZLL bulbs acting as repeaters for ZHA devices. This surprised both myself and @vlad as we both thought that this was not possible from what we’ve read in the past!
This kind of supports my anecdotal evidence in the past of the bulbs improving my mesh in the kitchen since their introduction.

Yes before you ask I can see that the profileId is:
03 C05E 0210 02 09 1000 0000 0003 0004 0005 0006 0008 0300 FC0F 01 0019
clearly showing as ZLL.

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How do you generate the table?

Not something I can do, @vlad did some magic from his end :slight_smile:

It shouldn’t be surprising. We’ve discussed this issue in the past.

Any ZLL device is supposed to, per the standard, be able to “fall back” To ZHA if paired to a ZHA coordinator.

Consequently the bulbs paired directly to the SmartThings hub, whether they are from Osram, Cree, GE, or Hue Will fall back to ZHA. They continue to self identify as ZLL, but they are functioning as ZHA devices.

That then brings up the whole question of repeating. Technically, these bulbs should act as ZHA repeaters When on power, and community members have posted Zigbee maps for over a year showing that that does sometimes happen.

So why only sometimes? As best we can tell, there seems to be a timing issue with the bulbs, and they just don’t always succeed in repeating.

We have a community FAQ on that. @vlad might find it interesting as well. :sunglasses:


Yes, this could be the reason why I’m getting such poor stability with my sensors! I’m going to shift all my osram lights over to Hue bridge over the week to see if this improves things.

Also, the zigbee mapping FAQ shows some maps with Hues acting as ZHA repeaters. :sunglasses: Note that those bulbs are connected directly to the SmartThings Coordinator, not using the hue bridge.

I completely removed all my Osram bulbs (direct connected to ST), and ever since my Zigbee mesh has been rock solid. I too have been working with ST on Zigbee problems I was having, and we ultimately worked out scenarios that led us to removing the bulbs. Except some of my old PEQ sensors having a few hiccups, my Zigbee devices are happy campers.


I dont know what all bulbs you have, but from my experience… I had about 20+ Cree Connected bulbs. At some point my zigbee mesh went to shit. Well bulbs went to shit. I started buying ST outlets to try to add some more well known repeaters, then added a bunch of iris brand sockets. Nothing I did seemed to help my stability with the bulbs. The Osram gardenspots were affected as well. I dont have too much else but lights and a few motion sensors so I couldnt fully tell you what all might be screwy.

So got a hue hub and paired all bulbs but like 8 to the hue removing them from st. From that day forward I’ve had great reliability. I swear there’s a bug or something once you get too many lights lol. I dont know about basic osram bulbs, but i thought that the rgb or rgbw lights dont pair with hue, i could be wrong so dont take my word for this.

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Pretty much describing my experience with osram instead of Cree. I’m really hoping this is the root cause of all my troubles. As my system has grown it has become a full time job monitoring and fixing stuck sensors. Adding repeaters made matters worse.

Good luck, but heres a 58 reply thread of my adventure. I never had issues with my sensors, but I didnt have but a couple. I still think there is a bug somewhere when you pair too many of the same type of zigbee device lol. Makes no sense but the moment I reduced my bulbs on ST to like 10 it all went peachy.

Hmmmmm, following this now. I was having a huge problem with three zigbee motion sensors and a contact sensor, all in the same room. I had 3 GE link bulbs in the room as well, all attached to the ST hub.

I replaced all of the bulbs with hue bulbs connected to the Phillips bridge. I haven’t had a problem since then with my zigbee devices in the room.

Interesting. Thank you.


Have I mentioned that I don’t like bulbs. A lot. And I’ve been fairly immune to issues?

Just observations, don’t want to start that discussion here but feel it might be relevant. How can a mesh network perform if some of its nodes are constantly going on and off? In theory it should heal, but in practice…

Also in my house it would easily quadruple the number of devices which is a stress I attempt to avoid.

If they’re not repeaters, nodes going on and off is no problem. That’s what mesh was designed for.

If they’re repeaters, yes, it can be a problem. But smart bulbs can and should be left on power all the time. ( see manufacturer instructions.) There are many options to use for smart switches that will give you a tactile physical wall switch without cutting power to the bulb.

In the UK, Popp and devolo make a very nice battery operated wall switch to use with smart bulbs and community members have devised some mounts for them that will meet most peoples aesthetic requirements. In the US, there are two available “smart switch covers” that fit over the existing wall switch and solve the power issue. There are other options as well.

The issue for this thread is something altogether different-- The fact that smart bulbs attached directly to the SmartThings hub do not appear to repeat correctly for other ZHA devices. That’s true even when they’re always left on power. :disappointed_relieved:


There are places where replacing switches instead of a bulb just isnt cost effective or sometimes possible. Break even is about 3 bulbs. Considering a GE switch is about 35 dollars or so, a Cree bulb is about 15. So doing an individual lamp that isnt on a switched outlet, a bulb makes sense. That being said, yes they are a lot more problematic than a zwave switch in my experience.

As for the ‘on/off’ for a bulb being a repeater. Remember you arent turning off the power to the bulb just to the led :wink:

And as I pasted in my other thread, yes cree bulbs are repeaters. The support person said they were, just not sure of it was ZHA or ZLL. I dont think this really matters for me or the OP. Thing is we both tried other methods of improving the mesh. In my case, reducing the amount of bulbs on the ST hub fixed all my issues. I no longer pair to ST for bulbs.

If i had to do things over, I would avoid zigbee devices like a plague. I’ve had hardly any issues with my zwave devices comparatively speaking. It just perplexes me why my heatmisers, nest and hue have no issues in my house with zero care for placement. While ST just struggles even though I give it plenty TLC and move everything away from it both channel wise and physically.
I think ST is just a heck of a lot more sensitive and very little tolerance built in for interference in the real world.

There are a lot of different ways to handle the possibility of interference. Many zigbee devices do channel hopping where they will adjust the frequency to find the least crowded channel. SmartThings does not do this.

Based on recent reports, it also looks like there may be QOS issues when zigbee bulbs are paired directly to the SmartThings hub rather than through the hue bridge. SmartThings may think the bulbs are ZHA repeaters And the bulbs may be dropping messages. Various different reports about this over the last 15 months, but several people have posted that removing all their zigbee bulbs from their direct connection to the hub solved a lot of zigbee network problems for them. That would be unfortunate if true, but at least it would explain why some people have such awful problems and other people don’t have any.

You can always blame wifi

But then again, it could just be local Wi-Fi interference. I’ve mentioned before that I have two provable instances of Wi-Fi interference at my house. In one case I have a Wi-Fi booster. If I put it on one wall in a room, it kills connection to all the SmartThings zigbee devices that are west of it. If I move it 90° to a different wall in the same room, everything runs fine.

And in another case, on weekdays around 330 my SmartThings arrival sensor goes bananas and keeps losing contact to the hub. In that case I suspect that one of my neighbors has boosted Wi-Fi and a kid who gets home from school around that time.

Does success require limiting approved devices?

It’s always true that in the US in a home automation set up zigbee is somewhat more fragile indoors than Zwave. There are a lot of ways to address that, with channel hopping being the most common, and obviously Phillips Hue is very successful even for people with very little technical background. And there are a lot of security systems which use zigbee devices with no issues after installation. But both of these recommend using a specific set of pre-approved devices.

It may be that the versatility of SmartThings and allowing for pretty much any ZHA device to be attached to the hub just opens up too many points of vulnerability. That would be sad if true, but at this point I would believe it. :disappointed_relieved:

@johnr @Sticks18 @erocm1231


I just have to chime in here and say I have zero Z-Wave devices (all ZigBee even with several direct connect hue bulbs) and my network is rock solid!! It self-heals and has never been more reliable than it has the last couple of months. SmartThings has made great strides to make the cloud stable and my network reflects it. Now to be fair I have an engineered ZigBee network it didn’t just happen. I have placed ZigBee repeaters inside and outside my house to create the network. The Hue bulbs are not relied on to route traffic but they don’t interfere with it either. We also live out in the country so interference from my neighbors is not an issue. Our WiFi routers and hubs are able to frequency hop around the SmartThings’ locked in frequency so that hasn’t been an issue.

ZigBee has a very clear future and is here for the long-hall. I can’t can say the same about Z-Wave.


Are your zigbee repeater devices transmitting at higher power than your Hue bulbs?

It occurred to me that, at least in the US, we ought to be able to select repeater devices and lay a backbone in such a way that the zigbee bulbs wouldn’t be likely candidates for route selection.

In the UK the zigbee range is extremely poor. My observation is that something in adjacent rooms struggle to reach each other. I’ve no experience of the boosted version you guys have in the US. Maybe that fares better?

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Yep my main ZigBee repeaters are the 63mW versions of the xBee Pro. That is what I use in the CoopBoss and since the chicken coop is about 400’ away from the house it covers the whole south side of our yard and all the hue bulbs we have in our landscaping connect to it. I have a couple more xBee Pros in other locations around the house.

I believe in Europe and Great Britain they are limited to the 6.3mW version. In theory that just means more repeaters. But as I think about it I may not have problems with my bulbs because my routers are putting out 10 times the power they are and they don’t really have a chance to interfere with anything. Who knows?? Just know ZigBee works great for me!!