High Latency on APs - bouncing the AP seems to resolve the issue

[Kleverett]

Hi all,

We currently have a case open with Meraki going on 6 days now. At multiple sites we've been seeing sporadic issues with our clients passing traffic through access points. When we look at the AP in question we are seeing high latency from it (100ms+). We bounce the AP and everything is seemingly good from there. Wanted to post our situation here to see if anyone else is having this experience as we wait for support to take a look at our latest packet capture.

Thanks!

[Ryan_Miles]

What model(s) AP?

What firmware?

Happening on all SSIDs or just some?

Happening to all clients or just some?

[Kleverett]

Hi there.

MR45/46 

Firmware MR 28.5

I have yet to confirm that it is happening on all SSIDs as our staff currently only has access to 1 SSID, but you raise a good point. We are starting to look into our radio settings now.

One Hypothesis right now is potentially looking at changing the Minimum bitrate configuration to Per Band as we have 2 sites in our organization that have not reported issues and their minimum bitrate is set per band while the sites having issues are configured per SSID

Thank you

[PhilipDAth]

I have seen this caused by Windows power saving.  On a Windows 10 machine, try this (which disables power saving for the WiFi NIC):

powercfg /SETDCVALUEINDEX SCHEME_CURRENT 19cbb8fa-5279-450e-9fac-8a3d5fedd0c1 12bbebe6-58d6-4636-95bb-3217ef867c1a 0
powercfg /SETACVALUEINDEX SCHEME_CURRENT 19cbb8fa-5279-450e-9fac-8a3d5fedd0c1 12bbebe6-58d6-4636-95bb-3217ef867c1a 0

Another common cause is WiFi driver bugs.  Try checking the manufacturer of the WiFi chipset for driver updates.  Note that the OEM (Lenovo, Dell, etc) often don't publish the current version of the driver.  Hence the need to check the WiFi manufacturers web site.

I hope this is on 5Ghz.  2.4Ghz is very problematic and issues are common.  Can you disable 2.4Ghz on the WiFi to get rid of this problem area?

[YC2]

Running into something similar. Clients on the ap can associate and authenticate just fine but user traffic has such high latency its essentially unusable. If your only seeing 100ms your lucky... ours reaches 4 digits. Reboot and it's peachy until the next ap over, or the one on other side of building, does the same thing. Reboot, rinse, repeat.

Seems to have started a few months back and progressively getting worse. Happens across multiple platforms. Worked with support earlier after getting another example we could replicate. Captures indicated simple pings weren't making it to wired side of AP. Same client can roam to another ap and work just fine with no other changes other then walking away from the culprit AP.

Auto upgrade to 28.6 (from 28.5) was set to happen in a week. Forced it for overnight. Time will tell.

[WB]

There's been some chat around a bug fix noted in the 28.6 release notes:

'MR could enter a state where ADDBA requests would not be initiated, resulting in reduced throughput (Wi-Fi 5 Wave 2 MRs)'

@YC2would be good to know if 28.6 provides a permanent fix for you!

[Agus]

The problem happened to me to it happened with device using 2,4Ghz device, when i saw on dashboard most of client coonect/receive signal with 2,4Ghz a little device connect.receive using 5Ghz. I think 2,4Ghz already saturated even maybe on one of user still on download progress on there, i thnk that make high latency.  

[YC2]

While that's a possibility that's not what was happening here. My two test clients were on the same ap, with no other clients on it, on 5ghz.

After fighting the automatic firmware update scheduler all ap's at the site are on 28.6 now. Time will tell.