In the past few weeks, there have been a number of fixes/installs where installers have reported slow speed tests from the router, followed the connection, and found that the Gigabit PoE plugged into the ePMP radio is what is causing the issue. Every time, they have fixed the issue by replacing the Gigabit PoE with one of the 100 Meg PoEs. Another interesting thing to note, is that according to our head tech, each issue with the gig PoE has occurred when the PoE is nearby or resting on top of nearby electrical devices (in one case it was a UPS, in another case a subwoofer. Maybe coincidence, but I can't say). Specifically, the reported issue is that the download speed gets throttled down to 1 mbps or less, while the upload is unaffected. Has anybody else had a similar issue with the Gigabit PoEs? Do we just have a bad batch mixed in?
We have been seeing the same issue. When we replace the gig PoE with one of the older 100meg PoE's the problem goes away. We have had four of these in three weeks. I suspect, but can't substantiate, that this is related to some sort of interference from nearby electrical.
In one case the problem went away by moving the PoE away from the client's UPS. It was originally about 3' away. Moving it to the other side of the room, about 10' away, fixed it. We were getting about 30 mbps on our original testing. This dropped to about 3 mbps when near the ups and went back up to 30 mbps when we moved it.
One of the others was sitting on top of a 120 volt powered sub-woofer. Another one was about 18" from 4 romex wires carring 120 volts. The fourth I do not know the physical circumstances surronding. It was the first and we assumed it was a one-off sort of thing.
Anyone else seeing this? Anything different in the hardware inside the gig PoE that would make it more susceptible to interference like this than the old 100 meg PoE?
We are having the same issue as well, in very similar situations. We even had one that was caused by a UPS and one that was caused by a sub-woofer. The third was caused by several romex wires going by about 18" from the PoE. Here is how Cambium support responded to it:
"Solution/Suggestion Provided: That is true, when two power sources are kept near by then there may be EMF(Electro Magnetic field) occurs which may cause interference with the other one. So that, the speed of the Ethernet port may goes down. Yes, the 100mbps & 1gig POE adaptor hardware are different. Since its a 1gig port, it take very less time to pass more data. So, when there is an interference for less time will highly affect the speed. However, for the same amount of time when 100mbps POE adaptor is used, the speed is affected much. I hope this information is helpful and clear for you".
While that is true, I have never seen this with any other 1 gig PoE's even in small cabinets on AP sites with UPS, multiple PoE's, incoming 120 volt wiring, etc. I have never seen it with the ePMP 1 gig PoE's until the last few weeks. I suspect it is a bad patch of PoE's but that is not confirmed by Cambium at this point.
There suggestion so far is to put the PoE far away from EMF sources like UPS units. Most clients who have a UPS want the PoE plugged into it so that their internet stays up with their computer.
This is a recent problem, not something that is "normal" and needs to be addressed.
The POE power supply is a switch mode power supply meaning it converts to DC, switches it to high frequency AC, drops the voltage with a high frequency transformer and then rectifies and regulates the output. Which is fed into an coupling network an a direct injection connection. This means that there is no line transformers on the ethernet side to reduce interference from itself or other noise emitting sources. This is not really better than splitting the cable and adding power to pins 4/5 & 7/8 directly (which works btw).
The 10/100 power supply just removes two pairs from the data path so the radio doesnt try to use gigabit speed modulation which is susceptible to injection interference.
You can move the powers supply, wrap it in aluminum foil or just set the radio to only do 10/100.