Tech+ Blog: Bay Area IT Security & Consulting News

Troubleshooting Meraki Wi-Fi: DFS Channels + Oakland Airport

Jul 10, 2018

A few months ago we solved an annoying Wi-Fi issue for a client using Meraki MR34 and MR18's. Normally the common Wi-Fi issues we get in the Bay Area is saturation issues. Everyone here uses Wi-Fi for everything and it becomes problematic especially when you are downtown San Francisco in the FiDi and it is floor after floor containing hundreds of access points and Macbooks all sending traffic over wifi. So you have to end up typically deploying more access points but on low power mode so that the channels don't get saturated. Mostly easy fix.

 

Oakland Wifi Spectrum anlysis network troubleshooting

 

This issue however was more unique. The client was in an environment that was average saturated and normally the wifi would work great. However several times a day it would just drop and performance would suffer greatly but a few min would go by and it was back to working just fine. It was as if they had a microwave oven without a door turning on and off at various times. You laugh, but that has happened. Old Microwaves can sometimes spew radiation and cause interference with wifi systems.

Well eventually after troubleshooting and research it occurred to us that this client is located in Alameda not too far from the Oakland International Airport. A quick search on the Reddit Meraki section lead me to this post. More testing and what we found was that radar systems use DFS channels and that by default Meraki Access Points will operate on these DFS Chanels unless you tell them not to.

 

Configure Meraki DFS Channels in RF Profile Tool

 

You can configure RF Profile's in the Meraki Dashboard with custom channels.
(Navigate to Wireless --> Radio Settings --> RF Profiles)

For a list of DFS Channels by country checkout this Wikipedia Page:
https://en.wikipedia.org/wiki/List_of_WLAN_channels

 

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