Posted: Tue Jan 18, 2022 23:59 Post subject: TP-Link TL-WDR3500 v1 unresponsive on big downloads/uploads.
Hi DDWRT team.
First and most important - Thanks a lot for all the hard work on the DDWRT firmware!
Now to the part which I am unable to find a solution for.
My setup -
WAN router - TP-Link TL-WDR4300 - Functions as WAN gateway without any issues. (r47692)
Second router - TP-Link TL-WDR3500 - Running on r47692. This router is configured in Client mode, as I want to keep the WAN and second networks separate, plus the second router is used only to service 2.4Ghz devices.
Problem - Second router is configured as a 'Client' on the 5 Ghz interface. The 2.4 Ghz interface is configured as the AP. All the devices are able to connect and hop on the internet without any issues in this mode.
The router freezes and all devices lose WiFi on 2.4 Ghz when a big download or upload starts, typically larger than 1 GB. This can be Google Photos upload or a Linux ISO download larger than 1 GB. Even the WAN router stops seeing second router as a client when it freezes.
If there is no upload/download which is big, the second router is rock solid and there are no issues whatsoever.
I have tried different revisions randomly going back last 6 months and this issue surfaces on all the revisions I have tried.
Large uploads/downloads do not affect the WAN router.
I suspect this might have to do with the 'Client' mode I am using, but I am unable to figure out what might be causing this.
CPU usage is consistently less than 20% and I have not seen free memory to drop below 50 MiB. Max IP connections is set to 4096 (default) and average connections I see across devices is around 400.
What am I missing? I do see some kernel errors in the attached log file, line 134, 135, 146 and 147.
Thanks in advance for any insights on this peculiar problem.
Joined: 08 May 2018 Posts: 14249 Location: Texas, USA
Posted: Sun Jan 23, 2022 12:48 Post subject:
560MHz single-core MIPS with 128MB DDR3 RAM. Dual-band router, 2x2:2. Perhaps you should post your wifi settings after you upgrade before filing a bug report. _________________ "Life is but a fleeting moment, a vapor that vanishes quickly; All is vanity"
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Linux User #377467 counter.li.org / linuxcounter.net
Posted: Mon Jan 24, 2022 7:57 Post subject: Additional configuration details.
Thanks egc and kernel-panic69 for your response.
egc - Per your suggestion I downloaded and upgraded to 01-21-2022-r48141 through wired ethernet. Well, things did not go as planned.
I had numerous problems with this build, as below:
As I had upgraded through the GUI without resetting, the router came up, but did not assign IP to any of the wired or wireless devices, even after restart.
I then did the 30-30-30 reset. I setup the WDR3500 as a Client from scratch on r48141. I encountered following issues:
1. The router connected as Client to the WAN router, but no internet on any of the devices on WDR3500.
2. I rebooted the router from Administration page, it did restart, but DHCP did not assign IP to the computer on wired or wireless interface, same as the issue I had encountered above.
I had to reset to get back into the router. Tried a couple of times and gave up. Went back to r47692, and setup everything from scratch. Everything is working as it should now, except of course the large uploads/downloads causing the router to freeze.
kernel-panic69 - My apologies. I should have posted router hardware details, my bad.
Please find attached my router settings.
All other setting are defaults. I have disabled the SPI firewall and do not use SmartDNS. No other special settings.
Please do let me know if any additional information is needed.
Joined: 08 May 2018 Posts: 14249 Location: Texas, USA
Posted: Mon Jan 24, 2022 16:15 Post subject:
Your wifi settings are not optimal for either build.
On 2.4 band, you should have short preamble enabled and ack timing of at least 1350. Not sure if this device supports auto-ack (setting of 0).
On 5GHz band, short preamble enabled, ack timing of at least 1350 as above.
This is just to start. There's probably other settings that you can test, but refer to the sticky in this forum and the wiki for guidance; do not use them as de-facto recommendations as they may not be optimal for your device and environment. _________________ "Life is but a fleeting moment, a vapor that vanishes quickly; All is vanity"
Contribute To DD-WRT Pogo - A minimal level of ability is expected and needed... DD-WRT Releases 2023 (PolitePol)
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Linux User #377467 counter.li.org / linuxcounter.net
I have updated the router settings, viz., enabled short preamble, enabled RTS/CTS protection mode with their corresponding setting. Also set the ACK timing to 1350 per your recommendation.
I'll run some tests and post back here with my findings.
Thanks once again for taking time to review the settings and the suggestion to tweak settings.
Joined: 08 May 2018 Posts: 14249 Location: Texas, USA
Posted: Mon Jan 24, 2022 21:16 Post subject:
kernel-panic69 wrote:
This is just to start. There's probably other settings that you can test, but refer to the sticky in this forum and the wiki for guidance; do not use them as de-facto recommendations as they may not be optimal for your device and environment.
This is just to start. There's probably other settings that you can test, but refer to the sticky in this forum and the wiki for guidance; do not use them as de-facto recommendations as they may not be optimal for your device and environment.
RTS/CTS protection is not always required; depends on the actual driver and chipset firmware loaded, for one.
Oh OK. It's working as expected now. I haven't tested with a big upload/download as I am in mid of the work day.
Any idea on how to find whether the current driver for WDR3500 supports RTS/CTS protection?
Thanks!
-Pranav.
Last edited by cyberpranav on Tue Jan 25, 2022 0:43; edited 1 time in total
Joined: 08 May 2018 Posts: 14249 Location: Texas, USA
Posted: Mon Jan 24, 2022 23:25 Post subject:
It's not so much a matter of whether or not it's supported; it's a matter of how those settings will affect functionality. AP modes don't necessarily require it being enabled. I literally had devices not being able to pull a search engine page whatsoever with the "recommended settings" sitting right next to the AP. Not sure if the standard vanilla upstream driver supports auto-ack (ack timing set to 0), I know what works in most scenarios I have set up and that is what I use; it may or may not work for others. _________________ "Life is but a fleeting moment, a vapor that vanishes quickly; All is vanity"
Contribute To DD-WRT Pogo - A minimal level of ability is expected and needed... DD-WRT Releases 2023 (PolitePol)
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Linux User #377467 counter.li.org / linuxcounter.net
It's not so much a matter of whether or not it's supported; it's a matter of how those settings will affect functionality. AP modes don't necessarily require it being enabled. I literally had devices not being able to pull a search engine page whatsoever with the "recommended settings" sitting right next to the AP. Not sure if the standard vanilla upstream driver supports auto-ack (ack timing set to 0), I know what works in most scenarios I have set up and that is what I use; it may or may not work for others.
That makes sense. I enabled it after going through the description in wiki and it has been working OK so far (just 6 hours of uptime for now), with no noticeable impact seen in speedtests.
I'll run some tests later in the evening and report with updates, if any.
Posted: Sun Feb 13, 2022 11:59 Post subject: some testing later...
I did a bit more digging on my 3600.
I tested my phone and my laptop. My phone can't crash the router - 3GB download finishes just fine.
However my laptop (Intel Wi-Fi card) does crash the router, but only on 5GHz. The quickest crash was less than a second from starting the download, but it usually lasts longer than that. It even completed the download a few times, but this testing was done without any other downs/ups on the network, which is an unrealistic scenario - normally just running ubuntu updates crashes the router.
top shows no abnormalities before a crash (sirq was 40% when it crashed, but I get it even higher when downloading stuff over wired connection without any crashes), and log does not show anything before the crash happens either.
I measured the power of the router, and while the brick is rated for 0.6A, the most I saw when doing a 5GHz transfer was 0.05A. Even 2.4GHz had a higher peaks of 0.065A, and it completed successfully, so it's not a power delivery problem.
When I found this thread, I optimized my Wi-Fi settings with the guide as advised, and it made the crashing worse - but it seems like disabling RTS/CTS and disabling RTS threshold made the crashing go back to the previous "frequency".
I also tried to switch 5GHz from HT40 to 20, but it made no difference - and my tests were crashing the router with the laptop being connected by HT20 and HT20SGI anyways.