MR74 Speed Issue

[AlexTauer]

Hey guys and gals,

Encountering an issue with an MR74 that I have providing coverage for the parking lot at the dealership I work for.

Speeds through the WAP spike at 30-40 Mbps down before dropping to 3-5 Mbps.  Upload speeds spike at 20-25 down, and drop down to 4-5.  All other access points provide 250-300 Mbps down, and 30-50 up, which is what our provider is showing our account to be set to.  This WAP was working just fine a couple weeks ago.

I have rebooted the AP, performed a factory restore, have verified that there are no cabling issue, and have verified that there are no settings differences between this WAP and the two others I have on site that are working.  All WAPs are running back to the same Gigabit network switch, which has not encountered any issues.

Anyone have any ideas? A coworker is thinking that it may be a heat issue (WAP is mounted to the side of the building, and receives full sunlight for a good 8-10 hours a day).  I have not done any temperature readings on the device yet, but they are rated for up to 130*F and I don't think that its getting that hot (I could be wrong though).

[rowell]

At what RSSI and SNR are the clients getting when you're performing the speed test? 

[Adam]

I was thinking the same things.  Possible interference nearby that AP?

[PhilipDAth]

Any chance you normally connect to 5Ghz and are now connecting to 2.4Ghz?

Any traffic shaping policies that have been applied?

[AlexTauer]

I believe that Adam may have pinpointed the issue.

The AP is mounted on the front of our building, facing out towards a major interstate (I-45 in Houston).  Looking through logs and the air marshal reports, I am finding that it is being bombarded with other SSIDs, more than likely from passing vehicles (seeing names like Gary's Silverado, Sharon's iPhone, etc.).  I'm also picking up our signal on the opposite side of the interstate (don't need to go out that far).  I'm going to try dialing back the transmission power a tad bit, to where its just covering our designated area.  Its going to take a bit of trial and error, but I think I can get it brought back in range.

I did also try changing the broadcast channel to one that is not as congested, so we'll see how that helps as well.

Thanks for the input guys.  I'll post back in a few days with the results of my tests.

[PhilipDAth]

Another option you could consider changing is the RX-SOP threshold.  This allows you to tell the access point to ignore weak signals (such as those driving by).

https://documentation.meraki.com/MR/Radio_Settings/RF_Profiles#RX-SOP

You could either get someone to come in who can measure it for you, or maybe get some machines placed just a little further away than where you want coverage, and adjust RX-SOP until they just get chopped off.

[AlexTauer]

Thanks for the suggestion!  I will try that as well.  

[80211WiGuy]

I think RX-SOP actively drops connected clients at the the set threshold and will still back off the channel if energy detect is triggered.  It's more useful for high density environments and forces clients to move to the next available AP.  I don't think it will improve this situation.

[80211WiGuy · Accepted solution]

Could be mounting height and/or heat.

Heat actually raises the RF noise floor in 2.4 and 5GHz, the AP might be rated to operate at higher temps, but no AP can operate well at high temps - it turns into an RF physics problem.

The long dipole type antennas commonly used on outdoor APs typically squish the signal into a flatter pancake than most.  Outdoor APs are also commonly placed too high for their attached antennas.  Its possible that your AP may be high up enough that your missing the main coverage lobe from the antenna, giving the birds great signal but not the users down below.