C8, Z-wave, a tale that took too long to solve (PoE Noise)

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tl;dr: Don't use cheap PoE adapters with the C-8. Unclear if more expensive ones are any better.

I've been struggling with Z-wave for months since I got my C-8. For months, zwave would just go completely unresponsive, and weirdly it would get messages, but couldn't send messages (so I'd get a notice about a door unlocking/locking, but I couldn't tell it to lock the door).

I've had several threads about this, and some of us in this boat found several solutions. Some it was interference from Lutron hubs, and some pointed to PoE adapters. I tried the first one, no change, but the second I was highly resistive of changing because I use PoE in my setup to put my hub in a central location.

Finally I got sick of it and swapped over to a straight USB power from a brick... Z-wave is 100% alive and working reliably. So I've been shooting myself in the foot now for months. =(

I've got some emails out to various vendors asking if they have RF measurements for their adapters. None so far have responded other than Uctronics who seems like they want to send me a replacement adapter rather than answering my RF question. And yes, I did try adding some ferrite cores to the power lead on the PoE adapter. No change. I did see this thread about someone modifying an adapter to fix the issue: https://groups.google.com/g/hermes-lite/c/0LQ_bw2S1Ik/m/FPkarb5dBAAJ?pli=1

Likely that other of these adapters that I used (and use) for my C-7 and C-5 also produced a crapton of RF, but it wasn't an issue until the external larger antennas were put into play.

Is anyone using PoE with their C-8 have a working PoE splitter (not just power, but also ethernet)? TexasPoE and Procet are the other two I contacted. I don't have any kind of Spectrum Analyzer to actually look at the RF noise coming from one of these splitters currently, though it does make me want to buy a TinySA Ultra or an RF Explorer.

And yes, I use Unifi gear... not super sure why that would be part of the issue unless they just generate noisy PoE and the adapter makes it worse.

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In general it's widely known that using a POE splitter with a unifi switch causes z-wave problems on the c8. Haven't seen it with any other switches.

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What about a Unifi POE switch that is powering many other devices (WAPs and RPis) via POE but NOT the Hubitat. Hubitat is located very very near the switch, but powered up with a small USB brick. I occasionally have unexplained Z-Wave issues.

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I think staff have indicated in the past to not use POE period. Not sure that is the official stance on them though. Maybe staff could clarify.

Interesting that these POE converter chips (all?) run at 250Khz, not sure if that would interfere with 2.4Ghz bands or not? I am not a RF engineer, but in my mind it is quite possible they could cause interference due to be a fraction of the Zigbee and Wifi band frequency.

Anecdotally POE in general seem to cause issues with Hubitat, not sure exactly why. But the theory of larger external antenna on the C8 makes sense if it is a RF issue. I wonder what would happen if you ran a shielded cable to a remote antenna a foot or two away from the hub?

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In general, isn't it a bad idea to put too many devices that generate wifi signals too close to each other? If you have a WAP and the Hubitat and maybe even a Rpi wireless signal in close proximity, won't they interfere with each other to some extent? Then add in a noisy POE adapter on top of it?

It seems like Z-wave (if you are in the USA anyway) shouldn't be close enough to the 2.4Ghz wifi/Zigbee bands, so I am not sure about interference being the cause here. But if it isn't interference and just poor power delivery or dirty power, maybe it is affecting the whole hub?

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I never had any issues with previous HE hubs. And yes, it is odd... but I found some indication of people showing loads of noise at 500mhz at least. One of the reviews for the uctonics has someone showing RF noise in a video. =/

It is a little disappointing that we all ask for PoE, and are told "nah" and instead "use a PoE adapter"... but then they cause this. lol. Makes me wonder if the reason PoE isn't an option is because of this very thing. I will totally admit I know PoE isn't exactly the cleanest source of power. =/

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Did staff actually say that? I thought they said the opposite, don't use POE adapters???

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None of my RF devies (Wifi Access Points or otherwise) are in close proximity to my Hubitat - however my Hubitat is literally sticky taped to the front of my rack about 4" away from a Unifi POE switch that is powering several POE devices...

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I have to wonder if this is just because Unifi users are more likely to use PoE (some light form of confirmation bias or something)

I guess I'm just curious if others have had any luck with a PoE splitter that actually works vs the cheapo one.

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It wouldn't hurt to move it a couple feet away as a test. It is free to try with maybe just a longer ethernet cable, and worst case it doesn't make a difference.

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I believe there are a few regular users using them with non-Unifi equipment and not having any problems. I don't think they are using any specific fancy splitter. Don't remember who exactly off the top of my head.

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We provide a power supply with the hub, and that is the correct way to power the hub. Once someone uses anything else, that person is on their own, and evidently problems can arise from this.

We won't be putting PoE into the hub for a number of reasons, not the least of which is that only a very small portion of customers want it, but it would add significant cost to the hub.

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Totally understood @bravenel. I don't mean to be argumentative, just wondering if RF compliance is one of the reasons. And yeah, understood as far as supportability, etc.

To be clear, I love HE and all you guys. Not dismissing the hardware at all... was more highlighting that simply adding PoE isn't a simple "drop this chip/inductor/cap into the HE hub and call it a day" when it potentially adds some extra issues to RF noise, etc. Nevermind that it would add cost/complexity/etc and satisfy very few users.

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I moved across the house with completely different cabling. No change.

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It was during the live stream of the C-8 announcement... something to the effect of "adapters are available, use one". No implications of support, etc. Just that they won't be adding PoE, especially when you can find adapters. In this case, it bit me.

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That I don't know. One way to find out is move it away from the unifi switch.

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Hmm, I will have to go back and watch that. But I do remember talk of even before the C8 that it wasn't recommended to use them.

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I use cisco catalyst POE switches with cheap splitters for hubitat, lutron and hue on c8 and c7 and have no issues.

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my lutron has no issues. My C-7 to my knowledge had no issues. The C-8 though, hated it. Zigbee was completely fine. Z-wave was not.

What splitter are you using?

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This one... but I am not using a Unify switch
https://www.amazon.com/gp/product/B087F4QCTR

The switches I use. I have a few of them throughout the house.

Cisco Catalyst WS-C3750X-48P