Strange Zigbee Motion Sensor Behavior

I moved my Smartthings hub to troubleshoot my Ring doorbell wifi/poor video quality to another location in my house. I also changed my Wifi 2.4ghz band to channel 1 (as my ST Zigbee channel is 20). Since doing this, my 2 Zigbee motion sensors (one is first gen, the other second gen ST branded) keep losing connectivity with ST and I have to pull the batteries out of them to get them talking again. One of the motion sensors, is no more than 50 feet from where my current ST hub is (although behind 2 closed doors). My other Zigbee devices (ST open/close sensors) are all working fine which is making this more perplexing because if I was having interference issues with Zigbee, I would imagine my other devices would be impacted as well.

Anyone have any clue why my motion sensors are acting strange?

On the plus side, I believe the move and channel change has had a positive effect on my Ring doorbell as the video is no longer choppy.

The stronger the Wifi, the weaker the nearby Zigbee will likely be. They coexist in the same band and Wi-Fi is a much stronger signal, so it almost always wins the competition.

The zigbee channel for the SmartThings hub is assigned at the factory and cannot be changed after that. So the first step is to go into your IDE and see what zigbee channel you are on. Then assign your Wi-Fi channel to be as far away as possible.

Note that the channel numbers are not the same. WiFi channel 11 is actually far away from zigbee channel 11.

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I was reading this page …

… a few days ago. It might help you as you may need to reboot.

As to why some zigbee sensors are affected and others are not, it may be just one particular repeater being drowned out and so its “children” can’t get their messages through. This does happen.

I’ve mentioned before that at our house we have a plug-in Wi-Fi booster. If I put it on one wall in one room, we lose connection to all smartthings Zigbee devices west of that. But if I just move the booster 90° to the other wall, suddenly everything works fine again.

I never bothered to track down the exact problem, because the fix was so easy. But this kind of thing is very common.

It’s certainly worth trying doing a network heal because your devices may find new paths that work better. Just unplug the smartthings hub (and take out the batteries if it has batteries) and leave it off power for at least 15 minutes. That will be long enough for all your zigbee devices to panic because the coordinator is off-line. Then put the hub back on power. It may take a few hours, but all your Zigbee address tables will be rebuilt for the current optimal routing. So you may not see the results of this until the next day, but there are times when it can help a lot and it certainly can’t hurt anything.

I had similar problems three times over the first year. Several of the ST zigbee sensors just stopped responding. Each time was after ST platform side changes or periods of instability. I had to delete and re-add the devices to get them to respond again. Some of the failed ST zigbee motion sensors were only 7 and 10 feet from the ST hub.

It has not happened in the past nine months. During that time I have never moved my ST v1 hub and I have a different wifi router than I did when the zigbee problems happened.

In case it helps, the router I had during the zigbee problems was the ASUS RT-AC68U. That was demoted to wireless bridge in the family room. The new router DLINK DIR-890L sits in the same room as the ST hub but 10 feet away. No noticeable Zigbee issues since I made that change.

There are definitely many different reasons why devices might stop working. Platform changes definitely among them.

In the OP’s case, since the Wi-Fi recently improved significantly, wi-Fi interference is the first place I would look. :wink:

Agreed, but in my case precisely setting WIFI channels to minimize interference didn’t help prevent the second and third instances of failure. Who knows? Just sharing my info to help. :expressionless:

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Thanks! The diagram you posted below is what I used to make my determination that I should switch over to Channel 1 for Wifi since my ST hub channel is 20. However, you bring up an interesting point as I made my Wifi signal stronger, I might have weakened my Zigbee strength. I am going to take your suggestion of unplugging for 15 minutes and see if that helps. I didn’t realize that performs a Zigbee network heal. I have tried rebooting their ST hub in the past, but never left it powered off for 15 minutes.

Also, @Dlee, my ST hub used to be right next to my Asus ac68u and I never had an issue. Now it’s next to my FIOS Actiontec MOCA network extender.

Best practices would call for the hub to be at least 3 m from your wifi extender. It doesn’t always make a difference, but sometimes it does.

And, yes, just a quick reboot or hub reset won’t force a Zigbee heal. You need to catch all the sleepy devices, too, so 15 minutes should do it. :sunglasses:

Also, when you unplug the hub, make sure you also take out the hub batteries if it has any.

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Thanks. I have a V1, so no batteries. If the network heal doesn’t work, I will try and move my ST hub further away from my network extender. I will keep everyone posted!

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Just remember to do the 15 minute power off routine each time you make a significant change in the physical location of devices. That includes moving the hub away from the router because the hub itself is a repeater in the network. :sunglasses:

So far so good! Since doing the power down for 15 minutes, everything is working perfect.

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My biggest problem was with my WeMo switches, If I changed the channel I had to restart each WeMo switch, not a big deal but sometimes WeMO was funky. Now that ST fixxed the WeMo integration things are much better. My WiFi is channel 11 and my Zigbee is channel 15 so there is a big space between the two. That is if I am reading the above chart properly.

@JDRoberts Thank you again for your help. Since I powered down my hub for 15 minutes, I haven’t had a single issue with these zigbee devices. I have been an avid follower of these forums and this is the first time I read about the zigbee rebuilding process.

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