Meraki wireless mystery: same slow speeds even after upgrades

[MerakiCurlz]

Hey all, hoping someone can help me unravel a puzzling Meraki wireless performance issue. We're seeing surprisingly slow download speeds, consistently under 60 Mbps, during peak hours (9 am-5 pm) when connected to our MR44 and MR56 access points. This is happening despite a seemingly robust network backbone: our Meraki MX250 firewall uplinks to an MS355 core switch at 5 Gbps, and the MR44/MR56 APs are connected to the MS355 via 10 Gbps ports, with verified 5G/full duplex uplinks from the APs themselves.

We have a total of 15 MR44s and 4 MR56s. My client, MacBook Air M2, confirms it's on the 5 GHz band (with the MR56 set to 80 MHz), and band steering is enabled. We're running three SSIDs (IoT, BYOD, Business). In our most congested areas, we see about 20-30 clients per AP.

What's really throwing me off is that speeds significantly improve after 6 pm, suggesting a load-related problem, but I can't pinpoint the bottleneck. I've already checked the Meraki dashboard to confirm 5 GHz connectivity, used Fast.com for speed tests, tried multiple APs and client devices, verified no client limits or throttling, and even disabled some content filtering on the MX250 to rule that out. I recently upgraded from an MX85 to an MX250 and added two MS355 switches specifically to improve uplink speeds to the APs, so I'm scratching my head as to why we're not seeing the expected performance.

What should I be looking at to get these wireless speeds where they should be?
Any suggestions or diagnostic steps would be hugely appreciated!

TLDR; We just upgraded from 1Gb to 5Gb; MX85 to MX250; added 2 MS355 48-port and are still receiving the same slow speeds.

ISP --5GB--> MX250 --10Gb fiber Uplink to--> MS225 stack--> --10Gb fiber Uplink-->MS355 --10Gb port--> MR44/MR56 APs

[Mloraditch]

Here is a helpful Cisco Live presentation that looks at a lot of things regarding wireless issues: https://www.ciscolive.com/on-demand/on-demand-library.html?search=2399#/session/1750271939049001zlpX

[ga123456]

A few places to check would be:

1) Have a look through your general wireless stats and RF health:

- Wireless>Monitor>Health
- Wireless>Monitor>RF Spectrum

Look for packet loss and high channel utilisation.

2) Since you have a device that can replicate the issue, have a look at the Clients page for them
- In particular go through the Performance tab
- Also looking at roaming times and other stats under Timeline, verify the device isn't constantly switching between bands or roaming between APs etc

3) Have a look at things from the Macbooks perspective, I think it's Cmd+Click the WiFi symbol to show RSSI and other RF stats. 

4) Try changing these settings one at a time if applicable:

- Disable band steering

- Change channel width to 40MHz

- Disable AI-RRM   

[PhilipDAth]

Wow.  Where to start.

Are you using any RF Profile?  If not, you should.  Do this first.

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

When you examine each AP, what channel width has it chosen? Is the channel width the same when it is and is not working?

Note that in a business area, using an 80MHz channel can often result in WORSE performance, because the WiFi infrastructure has to wait for the entire 80MHz band to be free.  You only need one adjacent business to be using part of it, and you can't transmit.

You often get a HIGHER throughput with smaller bands.  The standard for built-up business areas is 20MHz.  This is because it is far easier to find a single 20Mhz channel that is free and you can transmit on whenever you want.  If you are using an 80MHz channel, then try reducing to 40MHz or 20MHz.

Have you got AI channel planning enabled?  It can resolve many issues by learning about your environment.

https://documentation.meraki.com/MR/Radio_Settings/AI_-_RRM

Once you have an RF profile applied and adjusted your channel width, wait 24 hours, and then review Wireless Health and Wireless Overview to see if they provide any hints.

[PhilipDAth]

Also, from an affected machine, try going to:

http://my.meraki.com/

And see if it shows anything interesting.  Has it attached to a reasonable access point (as opposed to one far away).  What percentage of the traffic on the band you are using is consumed (both 802.11 and non 802.11).

How do the results compare when the issue is happening versus when it is working ok?

[PhilipDAth]

Also is the performance ok if you plug in via a wired connection?

[MerakiCurlz]

No wired connection are getting 500-900Mbps.

[KarstenI]

There are already good advices shown. But there is one more that caught my attention:

"with the MR56 set to 80 MHz"

You explicitly mention that the MR56 is configured with 80 MHz, but what is it for the MR44s? If they are using 40 MHz, this could partly explain the problem. Clients tend to stick to APs with more potentially throughput also if that AP is not optimal.

If not already done, use the same Bandwidth on all APs. And without knowing your environment, I would suggest to use only 40 MHz unless you know that 80 MHz doesn't cause any problems.

[jedimaster]

I agree with what others have said.  I would not use 80 MHz bandwidth.  Cut it down to 20 MHz, then analyze the spectrum, find out where the neighboring transmitters are (frequency), then map out your frequencies to stay as far away from any other transmitters as possible. Also, legacy acces on 2.4 GHz for older devices will absolutely cut your throughput.  Try to stick with 5GHz if possible, use non-DFS channels as well.  

[KarstenI]

>> "use non-DFS channels as well."

I think there is a "non-" that doesn't belong there.