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Comment by eqvinox | Hacker News Reader

> There are multiple PoE standards.

No, there aren't, not in the way you imply. There is the IEEE 802 PoE standards, which are all compatible (save for not enough power), and designed to carefully negotiate and especially never break non-PoE devices. And there is bullshit (sorry) like "Passive PoE" that is ironically an active violation of the IEEE specs, can break pretty much anything, and you shouldn't buy so the likes of Ubiquiti and Mikrotik finally get the wallet vote and stop f*cking doing. Unfortunately, the proper PoE PD logic is a few dollars of extra expense.

Yes, there is a slightly higher risk of killing devices due to faults in the PoE supply logic. I have the official PoE HAT for a RPi 4. I have to say it is somewhat poorly designed due to space constraints; the isolation between 48V and 3.3V should be better. I'm not even sure the RPi PoE HAT is spec compliant.

But I don't think you can/should blame this on PoE.

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I have a ubiquiti 30w poe+ injector that somehow doesnt provide enough power for 20W aruba AP. When I plug it in a 120W switch it works unless the cable gets too twisted or something. I vote not awesome

> I have a ubiquiti 30w poe+ injector that somehow doesnt provide enough power for 20W aruba AP.

What's your cabling like? Contact Ubiquiti? Looking at the datasheet, I do not see any IEEE standards listed, so they could be doing their own thing:

* https://dl.ubnt.com/datasheets/poe/PoE_Adapters_DS.pdf

You don't mention a specific Aruba AP, but their AP22 stuff lists the needed IEEE standard and wattage:

* https://instant-on.hpe.com/products/access-points/access-poi...

Don't buy Ubiquiti. Personally speaking, anyone doing passive PoE (even if only on other device series you're not looking at) is automatically on my shitlist.

I'm not surprised they can f* up a basic PoE injector. The reason for doing passive PoE is saving a few bucks, on the back of safety and compatibility. Of course they would try to pinch hard on the PoE injector too.

Oh and I'd say they (together with Mikrotik) are responsible for 90% of the bad rep PoE gets. The IEEE 802 stuff really just works. And I say that having been part of rolling out 15000 people conference deployments with several hundred wifi APs in the span of a few days. The only real problem is broken cables, but the Ethernet link commonly fails before PoE is impacted.

Fwiw, I’ve had a few different PoE switches from Ubiquity and at least so far haven’t had any problems with the switches. My current one is the 48 Pro-Max etherlighting , and I have around fifteen PoE devices and it’s pretty much plug and play always.

I did have issues with some of their other products - eg an old CloudKey gen1 that I had remotely in my parents place that I think ran out of space to the point it can’t update itself and can’t compact some old mongodb.

Ubiquity only did passive PoE in the very early days. Everything has been 802.11 variants for a long while wow. The injectors that shipped a decade ago with my APs were all 802.11af.

https://eu.store.ui.com/eu/en/products/loco5ac

Still being sold with 24V passive "PoE"

(It's 802.3af btw)

The UniFi line has moved away from passive PoE. The "UISP" line is almost exclusively passive PoE, even for brand new products. Ubiquiti has proven they know how to make devices that support both when they transitioned the UniFi line, but they actively choose not to and to enforce the use of bad nonstandard trash with their new products in their ISP product line.

The majority of UISP devices they sell are all relatively old products. For example the 'NanoStation 5AC Loco' is a great $50 product that continues to work well, but it was released in ~2019. And they continue to sell new models of products that have been unchanged for over a decade.

In the last 2 years they've released very few new UISP products and you're right that they continue to be passive PoE. I suspect this is for continued compatibility with their older product line. Upgrading from passive PoE to active 802.3 PoE requires replacing the injector and maintaining passive PoE makes it easier to upgrade. And the UISP product line is really meant for wireless ISP operators, not consumers, where the risks of passive PoE are smaller.

Anyway, I agree with the sentiment, but I don't hold it against Ubiquiti too much for continuing to use passive PoE for their UISP line, since I think it makes sense for their customers. As so-so work around you can get a 802.3 -> passive 24V converter: https://store.ui.com/us/en/products/ins-3af-i-g

> And the UISP product line is really meant for wireless ISP operators, not consumers, where the risks of passive PoE are smaller.

I'm afraid that's not how it works out in actual practice, it's the other way around:

WISP devices are installed in random people's windows, roofs and chimneys. The injector might end up behind their TV set. If their TV doesn't work, they unplug and replug random things. Which will fry whatever has the unlucky pleasure of ending up on the output side of the injector. I'm unfortunately speaking from experience.

Meanwhile, people buying and putting up a wifi AP beyond their CPE wifi router tend to have a bit of understanding. If you told them to never plug anything other than the given device into the output side of an injector, it'd probably go reasonably well.

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