WRT32X irregular high latency spikes

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ian2000t
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Joined: 27 May 2020
Posts: 26

PostPosted: Mon Jun 01, 2020 16:10    Post subject: WRT32X irregular high latency spikes Reply with quote
Following on from my last post I've managed to get things running a lot better than they were. on my WRT32X running as an AP.

The main things I've done on the 5Ghz to improve things (web pages loading, and DDWRT UI) was to change these settings:

- Channel width - from VHT80 to HT40. My phone would only speed test at 11Mb set to 80mhz. Now gets full 80Mb download with this set to 40mhz.

- Enabling "Protection Mode" - setting it to "RTS/CTS" with a Threshold of 2340. Before I set this, pings were all over the place. Since setting this, they are very rarely over 20-30ms, even when running speed tests or video calls.


However, I've still got this odd problem I can't track down. I'm running ping tests from my laptop on the 5Ghz WRT32x wifi to 4 sources:

- 192.168.1.1 (my WDR3600 Router)
- 192.168.1.10 (WRT32X AP)
- www.google.com
- www.bbc.com

This is a diagram of my network - I'm pinging from the laptop.

[Image below]


All are very acceptible and stable - apart from about 5-10 times every hour, I get a massive spike in latency (500-1000ms) for all 4 of them. As I'm getting it just pinging the WRT32X AP (192.168.1.10), I think this is cause, and the others are a symptom of this. Sometimes it times out. They also conincide with RDP session pauses as well.


These are my ping logs over the last hour, but it's been logging and showing the same thing all day:

[Image below]


These are my current 5Ghz settings.

[Image below]



Has anyone seen anything similar? Anyone suggest anything I can try, or any logs I check to try and pinpoint it? If I can get rid of these weird spikes, the Wifi and GUI is now working fast and stable.

I've also tested this on the same laptop, wired to the WRT32x switch and these ping spikes are not happening. So, I believe it is to do with wifi.
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ian2000t
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Joined: 27 May 2020
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PostPosted: Mon Jun 01, 2020 18:05    Post subject: Reply with quote
Also tried channel 44 in case it was a DFS radar interference, but still getting the same on ping logs.
pbphoto
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Joined: 29 Oct 2017
Posts: 88

PostPosted: Mon Jun 01, 2020 21:11    Post subject: Reply with quote
What version of DD-wrt are you running?
What kind of laptop is this?
Are there any other clients using the 5ghz SSID on the wrt32xx?
Do the latency spikes correspond to bandwidth spikes on DD-WRT Status tab?

I'd recommend running 43136 or newer. I'm running 43306 on my 3200ACM. A newer version was released today. Check your 5ghz channel map for the UK - 136-lower HT40 would straddle DFS/weather radar frequencies in the US, Also, unless you have a good reason for separation of your radios, I would use the same SSID on all four radios and let the clients decide/roam. Make sure ath2 is disabled. Here are my settings for ath0 and ath1.
ian2000t
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PostPosted: Mon Jun 01, 2020 21:48    Post subject: Reply with quote
Thanks for the reply. I had to move from 80Mhz to 40Mhz as my phone (Honor 10) could only get 11Mb down for some reason I don't underestand.


I've got further with a bit of poking, but to answer the questions you've asked:

- version r42015. Can try a newer version.

- Laptop is a Lenovo Thinkpad E590. Fine when connected to the WDR3600 5Ghz.

- Was experiencing these drops on my phone connected to 5Ghz, so I swapped Laptop onto this 5Ghz AP instead of the phone (only client on it now) to run ping logging.

- No bandwidth spikes in the graphs etc.

- Will be merging 2.4 and 5Ghz later, but want to load test them each first. It would be harder to investigate issues when they are merged.


What I did find is that everytime one of these time outs/high latency spikes occur, this appears in the log file:

Jun 1 20:17:28 WRT32X-DDWRT daemon.info hostapd: ath0: STA [mac address] MLME: auth request, signal -45 (Accepted)
Jun 1 20:17:28 WRT32X-DDWRT daemon.info hostapd: ath0: STA [mac address] MLME: assoc request, signal -46 (Accepted)
Jun 1 20:17:28 WRT32X-DDWRT daemon.info hostapd: ath0: STA [mac address] IEEE 802.11: associated (aid 1)
Jun 1 20:17:28 WRT32X-DDWRT daemon.info hostapd: ath0: STA [mac address] RADIUS: starting accounting session 298CE4F4D3ED08B5
Jun 1 20:17:28 WRT32X-DDWRT daemon.info hostapd: ath0: STA [mac address] WPA: pairwise key handshake completed (RSN)
Jun 1 20:17:28 WRT32X-DDWRT daemon.info hostapd: ath0: STA [mac address] MLME: auth request, signal -45 (Accepted)
Jun 1 20:17:28 WRT32X-DDWRT daemon.info hostapd: ath0: STA [mac address] MLME: assoc request, signal -47 (Accepted)
Jun 1 20:17:28 WRT32X-DDWRT daemon.info hostapd: ath0: STA [mac address] IEEE 802.11: associated (aid 1)
Jun 1 20:17:28 WRT32X-DDWRT daemon.info hostapd: ath0: STA [mac address] RADIUS: starting accounting session 298CE4F4D3ED08B5
Jun 1 20:17:28 WRT32X-DDWRT daemon.info hostapd: ath0: STA [mac address] WPA: pairwise key handshake completed (RSN)
Jun 1 20:17:29 WRT32X-DDWRT daemon.info hostapd: ath0: STA [mac address] IEEE 802.11: authenticated
Jun 1 20:17:29 WRT32X-DDWRT daemon.info hostapd: ath0: STA [mac address] IEEE 802.11: authenticated
kernel-panic69
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PostPosted: Mon Jun 01, 2020 21:57    Post subject: Reply with quote
Which wireless adapter do you have in your laptop? Intel wireless adapters are sometimes problematic if you don't keep the drivers updated.
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ian2000t
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PostPosted: Mon Jun 01, 2020 22:00    Post subject: Reply with quote
kernel-panic69 wrote:
Which wireless adapter do you have in your laptop? Intel wireless adapters are sometimes problematic if you don't keep the drivers updated.


"Intel Wireless-AC 9260 160Mhz" - Driver version 21.70.0.6.

I'll take a look at newer drivers, but I'm not sure that's the cause as my phone was experiencing this first.
ian2000t
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PostPosted: Mon Jun 01, 2020 22:16    Post subject: Reply with quote
ian2000t wrote:
kernel-panic69 wrote:
Which wireless adapter do you have in your laptop? Intel wireless adapters are sometimes problematic if you don't keep the drivers updated.


"Intel Wireless-AC 9260 160Mhz" - Driver version 21.70.0.6.

I'll take a look at newer drivers, but I'm not sure that's the cause as my phone was experiencing this first.


Just tried the very latest 21.90.3.2 and still getting them. Actually, seems to be more frequent now...
kernel-panic69
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PostPosted: Mon Jun 01, 2020 22:29    Post subject: Reply with quote
If your phone and laptop are on the same AP radio, that might be your problem. I generally only connect mobile devices to the 2.4 band. I would have to find hardware information on your phone, but if it's got a Broadcom radio for wi-fi, that could also be culprit. Not to mention, Marvell wi-fi drivers for routers are still a wash, generally speaking. I don't think any mobile devices ever adopted Marvell hardware.
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ian2000t
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PostPosted: Mon Jun 01, 2020 23:12    Post subject: Reply with quote
kernel-panic69 wrote:
If your phone and laptop are on the same AP radio, that might be your problem. I generally only connect mobile devices to the 2.4 band. I would have to find hardware information on your phone, but if it's got a Broadcom radio for wi-fi, that could also be culprit. Not to mention, Marvell wi-fi drivers for routers are still a wash, generally speaking. I don't think any mobile devices ever adopted Marvell hardware.


They've not yet been on the same SSID at the same time. When these tests are running, the laptop is the only thing on that AP at all.

I generally use 5Ghz for any device that can, and keep all the older (raspberry pis, CCTV cameras) on the 2.4Ghz. If I can get both frequencies stable, I was going to just have one SSID though.

I think I've exhausted every setting, so I think trying a newer build is the only option.

Just had an hours Teams call and my video kept stalling for several seconds every 5-10 minutes. In between, runs sweet though.

If I can't find an answer to this, unfortunately the WRT32X might be going back in it's box...
kernel-panic69
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PostPosted: Mon Jun 01, 2020 23:28    Post subject: Reply with quote
You don't want to use a single SSID. That can create further issues. Linksys WRT AC series routers are great for wired ethernet, but the wi-fi leaves a bit to be desired. Your IoT devices need G-Only and WMM disabled, and connected to the 2.4 band exclusively. This has been discussed many times on the forum.
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ian2000t
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PostPosted: Tue Jun 02, 2020 8:22    Post subject: Reply with quote
Updated to r43306, but it's still the same. New attachment.

So, I'm stumped. Find it strange that no one else has seen this on DDWRT - I can find similar things on OpenWRT forums though.

I think I can rule out "client issues" unless the laptop and phone I've tested with are both affected by the same incompatibilty.

I can't think of anything else to test now - other than take WPA away and try network open, but that would never be a solution anyway, so seems a pointless test.
pbphoto
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PostPosted: Tue Jun 02, 2020 10:48    Post subject: Reply with quote
It should be a simple config for the 32xx since it is just acting as a WAP. Is operating mode set to "router" under 'advanced networking'? Do you have a simple network config with everything on a single subnet? Can you try connecting your laptop to one of the other 3 radios to see if the ping spikes persist?

just brainstorming here.
ian2000t
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Joined: 27 May 2020
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PostPosted: Tue Jun 02, 2020 11:40    Post subject: Reply with quote
pbphoto wrote:
It should be a simple config for the 32xx since it is just acting as a WAP. Is operating mode set to "router" under 'advanced networking'? Do you have a simple network config with everything on a single subnet? Can you try connecting your laptop to one of the other 3 radios to see if the ping spikes persist?

just brainstorming here.


No, it's set to "Gateway" rather than Router.

Yes, everything is on one subnet - main WDR3600 router is DHCP/DNS and deals with PPPoE connection. Ping spikes don't occur on the WDR3600 wifi (never more than 80-100ms when busy).

Not tried 2.4ghz radio - can do. The 3rd radio ath2 doesn't show up on this r43360 release.
pbphoto
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Joined: 29 Oct 2017
Posts: 88

PostPosted: Tue Jun 02, 2020 12:02    Post subject: Reply with quote
I have mine set to router per this guide: https://wiki.dd-wrt.com/wiki/index.php/Wireless_Access_Point

What is tcp congestion control set to under administration - management?
ian2000t
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Joined: 27 May 2020
Posts: 26

PostPosted: Tue Jun 02, 2020 12:05    Post subject: Reply with quote
Changed from Gateway to Router.
- Same issue.

Congestion is set to "Wedgewood" with the default values.
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