Hey all, posting this because I've spent hours troubleshooting and want to document what I found in case it helps others.
After migrating from my C-8 to the C-8 Pro, I noticed my existing Zigbee sensors went quiet, and I could not pair any new Zigbee devices (Aqara A1 humidity sensors). The hub shows Zigbee as ONLINE with a valid PAN ID, but nothing pairs.
What I tried:
Rebooted the Zigbee radio multiple times
Full hub reboot
Aqara hard reset procedure (10 second hold, wait 60s, then pair)
Ran the channel scan — every single channel (11–26) shows RSSI: 0 and LQI: 0
That last point is what concerns me most. All zeros across every channel is not normal — even background RF noise should show something. The radio appears to be reporting as online but not actually scanning.
The smoking gun:
I plugged in my old C-8 and attempted to pair the same Aqara sensors — they paired immediately, first try. Same sensors, same room, same distance from hub. The C-8 Pro won't see them at all.
I'm currently working around this using Hub Mesh — pairing Zigbee devices to the old C-8 and sharing them to the C-8 Pro — but this shouldn't be necessary and means I need to keep two hubs running permanently.
My theory: The C-8 Pro uses a different Zigbee chip than the C-8. After migration the radio stack gets into a bad state where it reports ONLINE but isn't actually transmitting/receiving properly. The channel scan is returning all zeros
seems to confirm this.
Has anyone seen this and found a fix that doesn't involve keeping the old hub running? Is this a known firmware issue? Would love to hear from anyone at Hubitat on whether there's a proper fix or if this is a hardware defect.
So redo the migration. Turn off old hub. Change your wifi to channel 6 or under and your zigbee to channel 25. Now shut down your new hub and unplug for 30 mins. (normally it's 1 minute but we want your zigbee devices to go into panic mode)
Power the hub back up and see how things behave.
After trying everything suggested in this thread and more, still no joy. The channel scan continues to show RSSI 0 and LQI 0 across all channels — the radio is alive on paper but not actually doing any RF.
For what it's worth, this appears to be a well-documented pattern with the C-8 Pro. A quick search of the community forums turns up multiple threads going back to early 2024 with nearly identical symptoms — Zigbee dead after migration, Z-Wave fine, devices listed but unresponsive, re-pairing fails even inches from the hub. It's not just me and it's not a user error issue.
My current setup is Hub Mesh with the old C-8 handling all Zigbee and sharing to the C-8 Pro. It works but it's not a solution — it means running two hubs indefinitely because the hardware I paid to upgrade to can't do the job on its own.
If you're hitting this same issue — especially if your channel scan shows all zeros — I'd skip straight to opening a support ticket rather than spending hours on the standard troubleshooting steps. That's time you won't get back.
Hopefully, Hubitat can identify whether this is a firmware bug or a hardware batch issue and push a real fix. Until then, Hub Mesh is the workaround. Very unfortunate.
Did you try swapping the antennas on the C8-Pro? Maybe the one on the 2.4 port is defective? Take an antenna from your C8 and put on C8-Pro? The port furthest away from USB is the 2.4 port.
Do you connect to Hubitat via ethernet or wifi? If wifi does that work fine? If you scan networks do the usual ones show up on the list?
Can you move the hub nearby a mains powered zigbee device (or vice versa) and try pairing it?
I haven't opened a C8 up before but if it doesn't void warranty you could pop it open and make sure it isn't something silly like the 2.4 antenna coax popped off the main board.
Maybe defective hardware but you don't know enough yet to make that call.
Thanks for the suggestions. A couple of things to clarify, though — the C-8 (original) doesn't have external antennas, so I can't swap one over. The C-8 Pro does have the external antenna ports, but the C-8 itself is internal only, so that's not an option here.
To answer your other questions: I'm on ethernet, not WiFi, and the hub is otherwise fully functional — Z-Wave works great, web interface is responsive, no other issues. It's purely the Zigbee radio that's broken.
The thing that keeps nagging me is that the migrated devices came over fine and were working — it's only adding new devices or replacing existing ones that fail. That feels less like a hardware defect and more like the radio stack got into a bad state during migration, where it can maintain existing mesh connections but can't do discovery. The all-zeros channel scan seems to support that — it's not scanning at all, just maintaining what it already knows.
At this point, I think this needs Hubitat support with actual radio diagnostics rather than more community troubleshooting.
You are correct, be sure to open a warranty case. If you'd like to get started before you submit the case, send me your hub id in a PM, and I'd be happy to take a look at your hub.
The C-8 (non-Pro) has external antennas - in terms of physical build, it looks exactly like the 8-Pro model (and the antennas are even interchangeable between the 2 models).
This is incorrect. The C-8 has external antennas. So you are apparently not migrating from a C-8 to a C-8 Pro, but some earlier Hubitat hardware.
Details can matter. There are issues that can arise while migrating from a C-7 or C-5; knowing what hub you have will alter the suggestions you receive on ways to fix the issue.
ZWave is one antenna, 2.4GHz WiFi and Zigbee are combined on the other. Since you don't know if the WiFi works then it could be the Zigbee radio/firmware or it could be the ext antenna or coax/connector inside the unit.
Did you at least swap the antennas to see if defective (they are dual band 900/2.4 antennas so interchangeable).
I doubt its the antenna but it takes a 5-10 seconds to rule it out.
Radio is not broken if devices are working. A failed pairing does not necessarily indicate a defective radio, especially if other devices are still functioning normally. There are several common factors that can cause pairing issues in situations like this:
First, the device being paired may not have been fully reset before attempting to pair.
Second, the hub may be attempting to pair the device through a 3.0 repeater and the device can't reach the hub.
Another possibility is that the new hub currently lacks sufficient repeating devices.
Lastly, if the old hub is operating on Zigbee channel 20, there may also be 2.4 GHz interference affecting nearby radios and overall wireless performance. In some environments, changing the Zigbee channel to a less congested option can improve stability and pairing behavior.
You may want to try a few things:
make sure the new hub is not on channel 20.
if you changed channel, allow the mesh to settle before attempting to pair (24-48 hours may be required depending on how large the mesh is)
We have seen instances when swapping antennas on a hub (not moving antennas over from another hub, but just swapping the antennas on the same hub) has resolved radio issues, even w/antennas that seemed solidy connected before the swap. Best to power down before switching the antennas.
Sounded from below like none of the ZIgbee devices were working...I missed the later post where he said they came across and were working. Time to make my coffee.
That is not a scan, it is just a suggestion that channel 20 was historically found to be prone to external interference in general, not on your specific hub. There is no smarts behind the message, in other words there is no routine that tests channel 20, or any other channel for that matter. Everyone gets that message on a C8 or newer.
I would not take that "warning" as any indication of failure or fault in the radio, just a suggestion that other channels may perform better in certain enviornments.
Same with channel scan, it is not 100% accurate, and I would not trust it as a determining factor of radio health. It is a tool that may help to find a clear (unused) channel.
ive seen this when i restore a cloud backup from my c8 pro to a backup c8 with no antennas and even inside a faraday box with just a slight hole for the ethernet cable i have had some devices that were in close proximity move over to the the backup hub right ofter the restore bufore i disable the radio.. ive had to then re-pair them in place once i bring basck up the primary hub.. i do this so if the hub totally dies and we are gone for months i can have the neigher swap it in place and hopefully get most services backup..