Manual Channel Assignments Return to Channel 6

[CraigBowden]

I have a problematic area on our third floor using MR46 APs (we have three APs there).  I keep changing the 2.4 GHz channels assignments to not conflict with each other (1, 7/9, 11).  After a couple of days, 2/3 APs keep reverting back to channel 6, which is not what I programmed them for.  We have a lot of interference on Channel 6.  Any suggestions to make this permanent?

[alemabrahao]

Are you trying to use 7/9 channels? Don't do that man, It will cause more problems.

2.4 GHz Channel Overlap & Adjacent Channel Interference

Without getting too deep on how wireless communication happens, when a station (Access Point, client device, etc.) has something to transmit, it must wait for the channel to be clear. Put simply, only one device can successfully transmit at a time. When overlapping channels are used, any stations (STAs) on those channels will transmit independent of what is happening on the other channels, causing a degradation of performance. Think of it like being between radio stations and having a mix of country overlapping on your favorite metal station. This type of interference is called Adjacent Channel Interference (ACI).

https://www.ekahau.com/blog/channel-planning-best-practices-for-better-wi-fi/

[CraigBowden]

We have a lot of problems on Channel 6 so I'm trying to find alternatives.

[alemabrahao]

I know It's complicated, but in that case, try channel 1 or 11, don't use other channels, It will cause overlapping on co-channels.

https://documentation.meraki.com/MR/Wi-Fi_Basics_and_Best_Practices/Channel_Planning_Best_Practices#...

[CraigBowden]

How do I stop the APs from going back to Channel 6 without me assigning it?

[GreenMan]

If you statically configure a 2.4 GHz channel properly, it won't move away from there.   Are you sure you haven't just chaned the config to amend the channels which can be chosen by the autochannel mechanism?   I would agree with the previous comment to stick with 1, 6 or 11 btw, whether you do this dynamically or via manual assignment.  Personally I'd stick with auto if you can, because this will take account of transient changes to background channel utilization.  Only go with static if you're finding the sheer number of channel changes actually create more disruption than it's worth.   Also;   assuming you have mainly dual-band devices, turn on band steering, if 2.4 GHz is proportionately over-utilised.

https://documentation.meraki.com/MR/Radio_Settings/Band_Steering

[alemabrahao]

I agree with @GreenMan, if It is possible to use auto assignment. And one more thing, if your customers are dual band? I personally prefer to have SSIDs separated by bands (One for 2.4 and one for 5ghz). Band steering is a good option, but I've seen some devices not working well when it's activated, so I'd be careful.

[CraigBowden]

The most common situation is two APs near each other both end up on Channel 6 and are interfering with each other.

[alemabrahao]

@CraigBowden  What MR version are you running?

[CraigBowden]

MR 28.7.1

[alemabrahao]

Strange, can you share your RF profile configuration?

[CraigBowden]

[alemabrahao]

Oh, I don't recommend setting the minimum bit rate to 1.

Low data rates
You must carefully plan the process to disable or enable data rates. If your coverage is sufficient, it is a good idea to incrementally disable lower data rates one by one. Management frames such as ACK or beacons are sent at the lowest mandatory rate (typically 1 Mbps), which slows down the whole throughput, as the lowest mandatory rate consumes the most airtime. Try not to have too many supported data rates so that clients can down-shift their rate faster when retransmitting. Typically, clients try to send at the fastest data rate. If a frame does not make it through, the client will retransmit at the next lowest data rate and so on until the frame goes through. The removal
of some supported rates helps the clients that retransmit a frame to directly down-shift several data rates, which increases the chance for the frame to go through at the second attempt.

Take a look at this:

https://cloudcontrolled.uk/wp-content/uploads/2019/03/High-Density-Wi-Fi-Deployments.pdf

[alemabrahao]

Things to remember when considering the data rate settings:

● Beacons are sent at the lowest mandatory rate, defining roughly the cell size.

● Multicast is sent on the range between lowest and highest priority, depending on associated clients.
● Do you really have 802.11b clients in your network? If you don’t, consider disabling the 802.11b data rates (1, 2, 5.5, and 11) and leaving the rest enabled.

● If you are designing for a hotspot, enable the lowest data rate, because the goal is to have coverage gain versus speed.

● Conversely, if you are designing for a high-speed network and for capacity, with already good RF coverage, disable the lowest data rates

[CraigBowden]

We're a medical clinic.  We have a guest WiFi and our internal with a few other less utilized networks (internet only).  For the guest speeds we limit them to 6 Mb/s.  I doubt we have any 802.11b clients.  I started in June and the Meraki Wireless network was already setup.  With the rest of our network it wasn't designed well.  I'm sure some tweaking is needed.

[alemabrahao]

ok, but think of it as an improvement, I've seen many customers have problems with the lowest data rates enabled, and after adjustments, we had considerable improvements. It's just advice. 😁

[CraigBowden]

I appreciate it!