I have seen this as well, but to be honest saw it from time to time on 19 code too. for a while on 19, I wa scheduling nightly reboots because of it, but on 19.08 I believe it was it got better to the point where I just restarted the 5GHz radio when needed, which became rare. I assumed I had an issue with hardware, perhaps I assumed wrong.
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I certainly agree and appreciate that, but there are limits to what WRT routers will achieve with wifi since the mwlwifi driver has been abandoned for years and wifi 5 is obsolete.
No doubt about the driver, but we have past evidence that shows @WildByDesign 's experience with the 5GHz band is not inherent to the driver, so it all depends on finding the bug.
Regarding WiFi 5, people will be using it for years to come. It's not obsolete.
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Flashed a 21.02-SNAPSHOT build some days ago on my WRT1900ACS and configured an iPad to only use this AP. Not a single connection drop in 3 days whereas it used to stop working after an hour at most with 21.02.1
Other clients (laptops, phones, etc.) never had such extensive issues, so I didn’t really care about it and just used the secondary UBNT APs for this client.
Thought about replacing the WiFi module (2 mini PCIe cards, although the original one is one double-sized board) with two Atheros WiFi6 cards, but dropped the idea as suitable cards are not really cheap and there’s no guarantee - choosing a different router is certainly the mainstream solution.
Sadly, I'm also considering chucking away $500 worth of hardware but it's not clear what router would be safer nowadays. To make matters worse, I use WDS which means I need to buy 2 identical routers and pray that they don't have further compatibility problems.
I was 3.5 days into testing mac80211 5.7.5 regarding the 5GHz band crashing when it did, indeed, crash.
So this particular problem with the 5GHz band crashing (requiring a reboot of the router to resolve) does not seem to be related to mac80211.
This seems far more complicated.
well, i do not use standard brands, i use 2 x turis omnia + AX cards update. Its a bit more expensive, but there are not much compromises.
On a WRT1200AC running Davidc502's last build, I added a script in the Scheduled Task (crontab) section to reboot the router at 4:30am each day. (I'm using the following method: https://openwrt.org/docs/guide-user/base-system/cron#references )
In my case, it's a router at a family member's house, so nothing mission critical would be happening at 4:30am. People who require literally zero downtime will have to find some other solution.
I don't remember any specific reason that I did it -- it was more just to cover all bases -- but I also haven't had any persistent complaints from them about 5GHz going down or anything like that.
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This is a good idea and something that I may end up having to implement. Especially since the 5GHz band seems to crash between 2-4 days, although generally not less than 24 hours. So this is likely what I will have to do.
Other suggestions to buy a separate wireless access point are solid recommendations as well. But it’s not something that I can afford right now. That would be a good choice for a lot of people, though.
I personally have too much stubborn determination to not give up on this yet. I was lucky enough to have $400 ($450+ after taxes) a few years ago to buy my WRT3200ACM, thinking of it as a good investment.
But this 5GHz band crashing may be out of reach. There is no logging of the crash. I’ve read previous bug reports suggesting that it could mean that the crash might be happening on the wifi chipset itself or within the non-open-source firmware blob.
The 2.4GHz band remains fantastic and reliable. So using only that may be an option. Or setting the router to reboot every 24 hours as another option but no guarantee that the 5GHz band won’t crash under 24 hours.
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If you wanted to bisect this, you'll need to create a debug build with extra logging to narrow which line number(s) the crash happens around. Perhaps log entering/exiting each function?
Just a thought...
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The firmware that is loaded into the wireless chipset is a closed-source blob... there is a hard limit on what can be changed.
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Yep, but I don't think this 5GHz band bug was always present, as many people saw stability with David's builds, so it might not actually be a bug in the firmware. I could be wrong. We'll have to have someone go back far enough to see, of course, which is time consuming.
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5 GHz radio needed a restart after 9 hours.. not sure when it went down, that's when I noticed it.. have it rebooting every 24 hours..
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I’m on day 3 now of uptime which seems to be the average amount of days for when my 5GHz band would crash.
Interestingly, my 5GHz network disappeared briefly and I thought for certain that it crashed as per usual. Plus I was actually expecting it to happen today.
The 5GHz band came back up this time on its own which surprised me and reconnected automatically.
The logs contained several lines with hostapd error:
STA-OPMODE-N_SS-CHANGED
These never showed up during normal circumstances for me over the past few days.
I am wondering if this is the situation that happens and usually causes the 5GHz band to crash (at least on WRT3200ACM). However, possibly, in this rare exception it went down briefly and came back up without the band crashing entirely (requiring reboot).
These are just my current thoughts at the moment, but the timing of it seems on par with when my 5GHz band crash usually occurs on average.
I don’t know exactly what hostapd error STA-OPMODE-N_SS-CHANGED means so I am still searching and doing some research about it.
EDIT: I am looking into hostapd.conf possibilities for disabling or restricting AP power saving capabilities.
Also, I recall Brainslayer over at mwlwifi GitHub issues mentioning many times in the past that mobile device power saving features cause lots of issues for mwlwifi driver.
@WildByDesign you are using the new patched version right? Do you recommend disabling 5GHz for people who need wifi to work reliably? Isn't there an alternative driver to mwlwifi?
No, there is no alternative driver - Marvell in their ultimate wisdom decided to write mwlwifi instead of adding the new chipset support to the existing in-kernel mwifiex driver. As a result, it's either mwlwifi or nothing.
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Wow, this is already in the Linux kernel - https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/diff/net/mac80211/agg-tx.c?id=v5.10.88&id2=v5.10.87
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I spent some time over the holidays testing a workaround for the 5GHz crashing issue that required a reboot to bring back up.
Every time that I experienced that issue, I was on channel 149 with driver default TX power of 30 dBm. That 5GHz band would always crash anywhere between 12 hours and 3 days of up time and the only fix was to reboot the router.
Channel 36 with driver default TX power of 23 dBm seems to fix the issue. I had 9 days of up time. Then I switched back to 149 briefly and it crashed as expected. I’ve been back on 36 again since then for another 7 days of up time.
I don’t understand why this is the case, but this is my experience with it. I don’t understand how one specific channel can cause a wifi band to crash. But things are so good now that I don’t want to mess with it.
WiFi is so incredibly great on my WRT3200ACM for the past 16 days when using channel 36 for 5 GHz band. 2.4 GHz has always been great.
EDIT: For the record, I should note that I have witnessed the 5 GHz band go down a few times on channel 36. However, it always came back up on its own within a minute and never required rebooting the router. Channel 149 required rebooting the router 100% of the time to bring the band back up. 149 seems to cause some sort of hard lockup of the radio.
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I don't remember what channel I was on using 21 train code, but I believe it was on 149 as well. I could sometimes just restart the radio, sometimes had to reboot.. Have been back on 19.07.8 for 5 days with no issues at all.
I actually had issues getting the wireless to work at all manually specifying the channel.
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This is great info, the past year I was unable to use 5GHz on my WRT1900AC but since yesterday this changed and I was unable to us 2.4GHz. Upgraded to 21.02.1 and now finally got both 5 and 2.4 GHz radios working again but now experiencing the occassional los of internet connection. (initially the 2.4GHz was not working but switching from channel 11 to 6 seems to have solved that)