I'm fairly new to Hubitat, a little over a month now. Everything has worked pretty well and especially been stable, but then today around 4:00 PM, everything I have that is Zigbee just went offline. Everything else is online and operating just fine. I rebooted the HUB thinking that might help, but still nothing and it is only Zigbee devices. I looked at the logs, but nothing really stood out (albeit I don't know everything I'm looking at). Anyone seen something like this before? Thanks.
I would do a shutdown from the Settings menu. Unplug the hub at the wall, wait a minute or so, then plug back in. See if a full power cycle like this helps.
Otherwise, maybe you have a problem like lack of repeaters, or a repeating device that is offline and affecting the routing of other devices. What do you have for devices, battery versus line-powered devices?
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My guess, too!
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If Zigbee radio went offline, the message would be showing in the message center at the top right of your hub's admin interface. A message would also be displayed on the Location events tab on Logs page.
If you had an event where the Zigbee went offline, I would create a warranty case, as that is unusual and may be indicative of a hardware issue:
Thanks for all the support! I struggle some with seeing the need for a repeater. Please keep in mind that all Zigbee devices have worked for a month now with hundreds of commands thrown at them. I can only remember one time where it didn't get the signal to turn off/on. I just chalked that up to an anomaly.
Regardless, and I can't explain it, but after trying to troubleshoot this last night for over an hour with zero success, I woke up this morning and it seems to be working ok. I haven't checked every Zigbee device yet, but most seem to be working fine. The HUB itself did jump from one IP address to another leading me to believe it must have rebooted at some point (again, I did this manually once, but the IP didn't seem to change at that time). Not exactly sure what the root cause was, but I guess I'll just continue to monitor it from here since it seems to be working again. Weird.
Zigbee changes constantly. Lack of repeaters is a huge thing. If you have no mains based zigbee devices and lots of battery powered ones, there will be issues.
I would also set a reservation for the hub in your router so it doesn't change ip.
I would also look at what zigbee channel you are on.
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The root cause is likely the lack of repeaters. The need for repeaters, is to safeguard Zigbee devices from radio interference. The stronger the mesh is, the more resilient your devices are against the interference from other Wi-Fi devices running on the 2.4ghz band.
In a mesh that is weak, even a microwave can knock out devices off the Zigbee mesh.
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My experience, from several years of running multiple zigbee networks at the same time, is that stable meshes have one zigbee repeater for every 4-5 end devices.
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I guess I don't understand how this works. I always thought that each device acted as a repeater so the more you had, the stronger your mesh network is. So a repeater is something else?
I only have 5 zigbee devices. One is in the room next to where the hub sits. Then another is in an adjacent room and then remaining in yet an adjacent room. I thought by having them sort of connected in this way helped with the mesh network, rather than having all of them a long distance away. Then I could see the need for something in between all of them to help strengthen the signal.
It appears my Zigbee network is on channel 20 (0x14). Thanks again for the help.
What are these devices? Are they line or battery-powered?
Most line powered devices are repeaters. Battery powered devices do not repeat.
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Sorry, I should have answered that. Honestly, I didn't even know battery-powered zigbee devices existed. They are all line-powered, either light bulbs or switches that plug into a wall socket.
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What brand bulbs? If Sengled then they don't repeat which is usually a good thing except if you need them to.
Also keep in mind that generally switching the power off to smart bulbs that do repeat is not the best thing - for Zigbee it's less of an issue than Z-Wave of course but with a sparse mesh it could cause extra complications / delay.
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not what you told me.. both my hubs have had zigbee go offline hence the rule to reboot when that happens. Is this now classified as a hardware failure.. should I replace both my hubs?
confused.
I did say "may be" 
When Zigbee goes offline is good to have the hardware checked out, especially if it happens within first 30 days of use.
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Thanks, but geesh this is confusing. First, people say you need more repeaters. Well, then I thought I already had that with any device. Now I find out that isn't always the case and if you have the Sengled brand of light then they don't repeat, which is guess what, "usually a good thing!" Huh? 
So you really want repeaters, just not too many repeaters? Again, kinda confused here.
By the way, I do have the Sengled brand for two of my light bulbs.
Totally get that. I have covers over most of my switches where the bulbs exist. It helps discourage people from doing that.
I'm at 37 days, but I still think I need to monitor it for a while and see what happens. It was rock solid stable up to that point. A lot better than Wink, which would easily go down somewhere in the house at least once a week.
Yep completely agree... it's a "good thing" because lights tend to get turned off periodically/inadvertently. I have 8 Sengled recessed lights and 2 in table lamps in my den. I actually replaced the switch with a smart switch and use Smart Bulb mode which decouples the physical switch to prevent power loss to the smart bulbs..
edit: also (I think) bulbs don't usually have room for a lot of memory internally which can impact routing even if they do repeat.
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Let me reiterate. More repeaters are better.
Most line-powered devices will repeat (Sengled bulbs are an exception).
No battery-powered devices will repeat.
A good ratio is 1 repeater for every 4-5 non-repeaters. So for a zigbee network with 85 total devices, I have 16 repeaters.
16 + 69 = 85
69/16 = 4.3 (ratio of non-repeaters to repeaters)
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That's great to hear. Usually a radio doesn't go bad suddenly. Is more of an issue when there were problems with it since day one. Unlike other protocols, (older) Zigbee devices had a choice of 2 variants to pick: Zigbee Light Link and Zigbee Home Automation and they differ enough to make it harder for a controller to support both. Their solution was to merge the two into one, Zigbee 3.0. Now, they also allow manufactures to modify the protocol, so not all Zigbee devices running a specific variant are created equal either.
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@JPW - here's a more comprehensive explanation.
Imagine someone has a much larger zigbee network than 5 devices (eg. like mine with 85 devices). Now, the hub is limited to directly communicating to 32 non-repeating devices that are in close proximity to it. So of my 85 devices, the hub talks directly to about 3 or 4, and all the others connect to the hub via repeaters.
Now imagine that those repeaters were bulbs, which someone can inadvertently remove power to by flicking a switch. When that happens, all the devices communicating to the hub via that bulb would lose their connection to the hub and drop off the network.
Sengled tried to prevent that from happening by designing a bulb that could not function as a repeater. Since these bulbs are not used as repeaters, switching them off by cutting power will not affect the rest of the zigbee network.
This being said, the general rule is to have plenty of repeaters on a network. An a ratio of 1 repeater to 4-5 non-repeaters works well.
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