Strange PoE issue between MT router and Omada AP

RouterOS General
1

I recently got myself an RB5009UPr+S+IN (which is fantastic) and a TP-Link Omada EAP650-Desktop access point that I want to run on PoE provided by the router.

Unfortunately, I’m seeing a weird issue where, shortly after booting the AP, its power LED starts flashing orange to indicate that it’s not receiving enough juice, and the transmit power on the 5GHz transmitter drops to practically nothing (like -90dB less than a metre away from the AP).

However, if I then pull the ethernet out of the AP and immediately put it back in again, or if I tell the RB5009 to power-cycle the ethernet port with a 0s delay, the AP reboots and subsequently operates at full transmit power without any further issues, (until the next time it gets powered down, and I have to do this stupid “boot-wait-reboot” procedure to get it running properly again). Interestingly, a soft reboot doesn’t seem to work; it needs to be a proper power-cycle.

The strange thing is, I only ever see the AP drawing around 120-160mA, (according to the PoE status in the RB5009), regardless of whether the AP is running normally or complaining about low power, and it never goes anywhere near the 440mA that the RB5009 is supposed to be able to output on a single port.

Furthermore, I’ve completely disabled PoE on all the RB5009’s ports except the one powering the AP, and the RB5009 is running on the 96W adaptor so there surely can’t be any power limits kicking in.

Also, the datasheet for the AP states that it will run fine on 802.3at but will disable the 5GHz transmitter on 802.3f, so the fact that it keeps the 5GHz transmitting at extremely low power while it’s complaining about the PoE seems odd to me.

Does anyone have any thoughts about what on earth could be going on? Defective AP? Defective router? Some kind of PoE compatibility problem between the two?

I don’t know how I could even go about diagnosing/troubleshooting such an issue…

Failing that, does anyone know of any other APs that might fit my requirements (desktop form factor, Wi-Fi 6, PoE-In, around £100)? The EAP650-Desktop was the only desktop AP I could find that supported both Wi-Fi 6 and PoE-In at a reasonable price-point. I don’t want wall/ceiling-mounted, and the next best desktop AP I came across was the UniFi U6 Mesh for nearly double the cost!

2

The Wap Ax (with its table stand) might do, though It has to be seen if its intended placement Is compatibile with the shape of its emission.

But what you report Is actually strange.
It sounds like an issue of some kind with power negotiation between the two devices.

Is It the same with PoE out forced on on the RB5009?

3

Designing properly standard compliant PoE devices (both source and sink side) is not exactly trivial, and manufacturing it costs significantly more than the “more-or-less if you look at it the right way” versions of the same.

Why not get a nice passive injector? There are actually ones available that have multiple ports, polyfuse (so self-resetting) protection per port, proper housing, etc. and are not the usual jumble of wires and wall warts. I usually avoid PoE if I can but otherwise go with these for APs.

4

It is the same with forced PoE, yes.

5

No spare sockets in the vicinity to run an injector, unfortunately.

The RB5009 has replaced an old router with built-in Wi-Fi, so I explicitly choose the PoE variant to be able to power an AP without the need for an additional power socket.

(The AP is right next to the router so it’s not a long cable run or anything; just a 2m solid core Cat 5e).

6

I have a 650 myself but plugged into a socket using the adapter ( luckily my wall mount is close to an electrical outlet on the other side of the wall.)
I have used injectors with no issue on other tplink and MT access points.
https://www.canadacomputers.com/en/power-injector/188906/tp-link-tl-poe160s-poe-injector-1-10-100-1000mbps-rj45-data-in-port-1-10-100-1000mbps-rj45-power-data-out-port-1-ac-socket-comp-tl-poe160s.html
Future proof it with this model → https://www.canadacomputers.com/en/power-injector/255651/tp-link-tl-poe260s-2-5g-poe-injector-tl-poe260s.html

another one.
https://www.amazon.ca/Compact-Injector-Capable-Delivering-Ubiquiti/dp/B09LK7DTPF?dib=eyJ2IjoiMSJ9.dO_zjzGtyGVzGInSPK6TYiKWEQKSg2dTmxAdgrgDp4tPm5zJGGWuEmB2lzPgAmx4ZGygP2lOKm9WWKa0p4_h8mRf7aug90A34fW9WglLZ0KoXQhFxCztFDez-uFP_SOtpfjvs9-GQlCXoAJ9xJZ11hzoLZ9Gg5g2uAa95vk5Cfv0VRLpbBFJzy5pZwadjsPdVfdAV132BqtpcIxhxwixS18Yw5sJJOUSrZ0SxquBAYOGFSXy0OV40fc5YmKAeg0Bly2PSzKFDZWNJM1LBrEV9OUs6uIFO9TZiJhCJ12Q4EU.a5En78WHsP1SLGZzHvRRxEeyhTHZdWSLGX7oAIuabi8&dib_tag=se&keywords=Ubiquiti+Networks&qid=1744464635&sr=8-6


Did you rule out the cable and connectors … Try plugging the AP directly into the 5009 and see what happens.

7

If the issue is the same with power forced on on the RB5009 it should mean some PoE related issue on the TP-Link side [1] :confused: .

You can try using a splitter/converter to extract the power (48 V i presume) and power the TP-Link AP with 12V/1.5A DC, such devices are commonly used for 12V cameras, only pay attention to get a Gigabit compatible one.



[1] which doesn’t mean that the TP-Link is defective or “wrong”, only that maybe it wants to chat to the PoE power supply (to negotiate some parameters) and the Mikrotik turns a deaf ear to its blabbering.

8

This is the third cable I’ve tried and it’s brand new. I’ve also tried multiple ethernet ports on the RB5009B with the same results.

9

Oh, I didn’t even know they were a thing! That could work if I can’t get to the bottom of the issue.

10

This just gets stranger and stranger…

I ended up borrowing a TP-Link unmanaged PoE switch (TL-SG1005P) and connecting it in-between the RB5009 and the EAP650 to see how the EAP would respond, and it functioned perfectly normally, with no sign of any insufficient power warnings or degraded Wi-Fi performance, so I assumed it must have been the router at fault previously.

However, when I subsequently removed the switch and reconnected the EAP directly to the router again, it was no longer exhibiting any of the previous issues, and since then I have been completely unable to reproduce the problem!

It’s almost like the EAP was stuck in some kind of abnormal PoE state out of the box, which caused it to not play nicely with the RB5009, but connecting it to a different PoE source somehow reset something, and now everything is working perfectly.

It’s bizarre!

11

Some sort of breaking in? :open_mouth:

Or the shock of being put into service?

The device had been resting peacefully for a few weeks or months in its comfortable padded box in a dark, quiet warehouse.
Then you first shake it during transport, then take it out of the box and start inserting plugs in this or that socket, and then you suddenly apply to its poor terminals 48V!
Maybe it needed some time to get used to it :wink:

12

Initial “pairing” with another TP-Link device unlocked it. :joy: