RF Interference due to power lines

[kcastellano]

Hi,

I have an AP 250 mounted in a classroom ceiling that was working without issue. Due to a recent renovation to a classroom above, power lines were run across and through the ceiling . These lines power a computer lab above this room.

After that point, wireless traffic has been problematic. Connections dropping, lag times, etc.

If I step into the hallway, there are no problems with connections. I've ran multiple tests: swapping APs, working with Aerohive and adjusting radio rates/configs, checking neighboring APs for interference, etc.

We have a deployment of about 200 . No other rooms have these issues.

Aerohive says the wifi issues are due to RF interference. Support has been excellent but they are leaning toward a physical issue with the room.

Has anyone see this and can offer any suggestions?

Thank you.

[dparsons]

If you have an android phone there are some simple wifi apps to show you if there are devices broadcasting in the area. One is called WiFi Analyzer. You also have tools in Aerohive to look at the spectrum as well as look at the ACSP neighbors and look for any devices on the same channels as the AP (or worse neighbor channels on 2.4 like 2, 3, 4, or 5) that have a signal strength above -80 with a BSSID that you do not recognize. You will likely see some of the other Aerohive APs but if there are any that are not Aerohive then that is what I would be looking for. If it is broadcasting an SSID then a plain laptop and a little stroll around shoud help you narrow down where it is.

So any chance they installed an AP in the laptop lab that you are unaware of? Or wireless microphones? Other items that come to mind are projectors, white boards, streaming devices.... All of these should show up with an SSID except the microphone.

As a last ditch effort you may have to enlist the help of the facilities crew to kill the power to the lab.

Happy hunting and good luck.

[kcastellano]

The lab above is a computer lab. Windows 10 Dell Laptops. I haven't done any RF analysis. Is there software or an app that would help with that?

I checked for microwaves or any other machines that could be adding inference. I will also check the room and see what is plugged in.

Thank you for your suggestions.

[dparsons]

Just reread the post and see you did say computer lab. My bad.

[dparsons]

Normally there are power lines run everywhere in a building and the frequency is no where near the 2.4 or 5 so unless it is laying across the AP itself (and even then) I would doubt it was the issue.

You said the power was to support a lab above this classroom. What type of lab? I know that Macs come with wifi built in and turned on by default and I think even broadcasting an SSID. If the lab devices have wifi turned on and are in ad hoc or AP mode they would easily produce enough RF to knock people off. I made an assumption that it is a computer lab. If there is other type of equipment that may be your issue too. Have you done any RF analysis to try to determine where it is coming from?

One extremely rare possibility is if it is a computer lab and there is a defective power supply that is pouring noise back down the power line? What happens if all the machines in the lab are unplugged?