I've been having this sort of problems too with the WRT1200AC. used to run WRT54G's in WDS mode and stable for a very long time until 1 fried up, replaced them with the former and I tried to add a dumb AP to my setup, started to discover all sort of issues , particually with the 5Ghz modem.
I tried to apply about everything I saw here on the forum to try to solve it. I'm using 2 different SID's between 2.4 and 5 , all my devices fall back to the 2.4 band/sid but the performance isn't really great there either on fast downloads it grind to a halt, but the 2.4 connection atleast seems to be stable
When I reboot the modem, I can see the 5Gh SID present, I can connect to them fine, using 3 laptops, an older one, one a few year, and another one 4 weeks old. They all show this problem, the oldest laptop "sees" the 5Gz a tad longer. Using Ubuntu 20.04 on the oldest and the newest, a windows10 laptop as well and also samsung S10 and a Oneplus6T , they all show the same behavior. It takes about 10 minutes to see them all use the 2.4Ghz SID instead of the 5Ggh
I tried release 21.02.x , 21.01 . I actually upgraded a while back from 19.x-is release because I wanted to create a bridge with a localport + wan port, that was working in 19.x , but moving towards the new switchport stuff , I couldn't get this to work. I just ended up throwing a real switch in the mix, but now that I'm diving deeper into this I'm discovering a lot more. The dump AP I added was functional, but all the sudden my laptops connected to the modem upstairs (2 floors up), and then swapped back and so on on the 5Gh band. I'm going to try to downgrade to a version in the 19.x branch to see if I can make it work there. One thing which is pretty cool, it's documented really well in the site here, I just discovered that it has 2 boot partitions.
I'm going to try the 19.07.7 release to see if that one is stable enough. Thanks for all the work though on openwrt, I really like it and hope that maybe the description of this issue helps:
PS:
OpenWrt 21.02.1 (Linux 5.4.154) - version that has issues
OpenWrt 21.02.0 (Linux 5.4.143) - same problem
OpenWrt 19.07.7 r11306-c4a6851c72 / LuCI openwrt-19.07 branch git-22.025.78315-f3debdc
Tested 19.07.7 and this one also has issues. I've been testing various settings and looking at the graphs, also tested cabled connection and downloaded a debian CD as well as large shape file archives (~1.5G) and lookin at how the graphs behave. I started rsync'ing the files between 2 laptops on the wifi and I in nowhere get the speeds I'm supposed to, being 5 meters from the AP with both.
Tried this:
- no encryption : no difference
- set width from 80 to 40Mhz : this seems to kinda take away the bottom peaks in the transfer, so the transfers don't totally stall anymore. Switching to 20Mhz width and the problem re-appears
- using different channels , 52 and 64 : both are totally free in my area, no difference
- using N instead of AC , this slows it down , but not by a lot
I'm reaching 1,544,384.23 bytes/sec on an rsync over 5GHz ...
The 2.4Ghz channel I'm not testing it anymore, it looks like it's suffering from the same problem but as expected, it penetrates further in my house, my TV is wired so netflix is limited to the WAN speed but I never had issues there, even watching 4K.
Took some screenshots of the graphs while transfering:
The drops are noticeable in the transfer I see the rate drop to very low levels and the file size on the receiving side isn't progressing. Now I understand how 5GHz works, number of antenna's, distance etc. The modem is in clear view of both laptops. laptop to laptop transfer , I would expect to see this to be faster than download test from the internet (1 is a linode machine I know transfers very fast , the other is the closest debian mirror)
Things I'll try is to install the stock firmware from linksys/cisco and test the hardware with it and see how this could make a difference. reluctantly though. But I'll add information here once collected.
UPDATE:
Quite the bummer, the stock firmware shows me the same issue , transfers are way too slow for the advertised speed rsync the full file :
GRB_20211216_30000B500_Shapefile.zip
785,158,784 100% 3.76MB/s 0:03:19 (xfr#1, to-chk=0/1)
I've never actually ran this firmware , flashed open-wrt when it came out of the box, I never realised how pathetically non-featureless this firmware actually is, can't even select the channel I know is empty, only goes to 42 . There is like nothing to tune in this stock thing
Since I have 2 of those, I can exclude the hardware since I swapped both , and now pretty much can exclude the firmware too. So is it my expectation that is way off ?
Reading as sold:
The Linksys WRT1200AC AC1200 Dual-Band Smart Wi-Fi Wireless Router is a simultaneous dual-band 2 x 2 Gigabit router, which supports 256-QAM modulation, allowing a maximum data rate of 400 Mbps on the 2.4 GHz band and up to 867 Mbps on the 5 GHz band.
Even theoretical max: 867Mbps is 108.37.MB/s which is a far cry away from my average 2.10MB/s transfer speeds (even multiply by 2 since i'm doing wifi-wifi transfers).
With the stock firmware doing a 5GHz -> 2.4GHz transfer between laptops is the worst, drops down to have MB/s at times, it's sick
glenn@zenny:~/$ rsync -av --progress GRB_20211216_70000B500_Shapefile.zip.1 glenn@192.168.1.177:
sending incremental file list
GRB_20211216_70000B500_Shapefile.zip.1
144,965,632 42% 382.92kB/s 0:08:30
I'm truly out of idea's here what the cause is.
root@router1:~# cat /sys/kernel/debug/ieee80211/phy1/mwlwifi/info
driver name: mwlwifi
chip type: 88W8864
hw version: 7
driver version: 10.3.8.0-20181210
firmware version: 0x0702091a
power table loaded from dts: no
firmware region code: 0x30
mac address: 00:25:9c:14:22:b8
2g: enable
5g: disable
antenna: 2 2
irq number: 74
ap macid support: 0000ffff
sta macid support: 00010000
macid used: 00000001
radio: enable
iobase0: dd8384dc
iobase1: 7921cfbe
tx limit: 768
rx limit: 64
qe trigger number: 22413
root@router1:~# cat /sys/kernel/debug/ieee80211/phy0/mwlwifi/info
driver name: mwlwifi
chip type: 88W8864
hw version: 7
driver version: 10.3.8.0-20181210
firmware version: 0x0702091a
power table loaded from dts: no
firmware region code: 0x30
mac address: 00:25:9c:14:22:b9
2g: disable
5g: enable
antenna: 2 2
irq number: 73
ap macid support: 0000ffff
sta macid support: 00010000
macid used: 00000001
radio: enable
iobase0: 8e3cc2c2
iobase1: 9723d730
tx limit: 768
rx limit: 64
qe trigger number: 22607