TL-WR841N v13 WiFi stability

Installing and Using OpenWrt
1

Hello OpenWrt community,

I'm experiencing wifi stability issues with a TP-LINK WR841N v13 router. As soon as there is traffic on the wifi of ~5MB/s for more than 1-2 minutes the AP disconnects all clients and is not visible any more.

Connecting to the router via ssh using a cable connection is still possible and there is nothing suspicious in the kernel or system log. The wireless hardware just seems to unresponsive. If this happens and I connect to the router than iwinfo scan does not show any wireless cells (there are around 40 in the neighborhood) and throws some errors in the kernel log:

[154618.269894] mt76_wmac 10300000.wmac: MCU message 8 (seq 3) timed out
[154623.389842] mt76_wmac 10300000.wmac: MCU message 8 (seq 4) timed out
[154628.509540] mt76_wmac 10300000.wmac: MCU message 8 (seq 5) timed out
[154632.109500] mtk_soc_eth 10100000.ethernet eth0: transmit timed out
[154632.115879] mtk_soc_eth 10100000.ethernet eth0: dma_cfg:00000055
[154632.122093] mtk_soc_eth 10100000.ethernet eth0: tx_ring=0, base=033dc000, max=1024, ctx=622, dtx=622, fdx=574, next=622
[154632.133146] mtk_soc_eth 10100000.ethernet eth0: rx_ring=0, base=033cc000, max=1024, calc=869, drx=870
[154633.629472] mt76_wmac 10300000.wmac: MCU message 8 (seq 6) timed out
[154638.749666] mt76_wmac 10300000.wmac: MCU message 8 (seq 7) timed out
[154643.869555] mt76_wmac 10300000.wmac: MCU message 8 (seq 8) timed out
[154648.989521] mt76_wmac 10300000.wmac: MCU message 8 (seq 9) timed out
[154654.109636] mt76_wmac 10300000.wmac: MCU message 8 (seq 10) timed out
[154659.230076] mt76_wmac 10300000.wmac: MCU message 8 (seq 11) timed out
[154664.349981] mt76_wmac 10300000.wmac: MCU message 8 (seq 12) timed out
[154669.469086] mt76_wmac 10300000.wmac: MCU message 8 (seq 13) timed out
[154674.589239] mt76_wmac 10300000.wmac: MCU message 8 (seq 14) timed out
[154679.709615] mt76_wmac 10300000.wmac: MCU message 8 (seq 15) timed out
[154684.828882] mt76_wmac 10300000.wmac: MCU message 8 (seq 1) timed out

After around 5 minutes the AP somehow recovers, notices that all clients are inactive, disassociates them and then the SSID of the router is visible again and all clients can reconnect.

I'm currently using the stable release 19.07.04 but it also happens with the development snapshot (last tested 16th of November)

The hardware site for this router suggests, that there used to be wifi stability issues for this device which are assumed to be fixed now

This used to happened like once month before but since I recently upgraded my ISP connection to a larger bandwidth this can be basically provoked by starting a download from a reasonably fast server, so I assume it is related to the wlan traffic.

Any Ideas how to fix that?

Regards

1 Like
2

I have the same one currently ... I think openwrt installs fine for it and for my 50/50 connection it can even do cake sqm but unfortunately WiFi is not stable. I think the MT76 driver is the issue. I wonder if there is a way to use the oem WiFi driver for it and openwrt for everything else ... otherwise I’ll have to use this as wired router and something else as access point ...

3

Well, there is a feed for the closed source drivers, which doesn't seem to be updated any more, i.e. it is not available for the latest kernels. I tried to build an image of 19.07.1 (kernel:4.14.167) using this driver, but loading it via modprobe reproducibly lead to a kernel panic. However I did not put to much effort into try to get this running. Also there isn't to much documentation around on how to use this.

https://github.com/Nossiac/mtk-openwrt-feeds/blob/master/about-mtk-wifi.md

The only thing which helped for the open source driver so far is limiting the downlink/uplink speed to around 25Mbit, which used to the speed, of my old ISP connection, which worked almost flawlessly.

I'm currently playing around with the tx bitrates but without success.

Regards

4

I tried the 19.07.5 release ... It works great for a few hours with my 50/50 connection with about 5-6 clients but after a few hours it becomes unstable. I think wired it works fine. I also tested building from latest git with Luci and it also works but I think its got the same issue of becoming unstable after few hours.

5

I can confirm that also the latest development snapshot using the recently updated MT76 driver (mt76_5.4.85+2020-12-18-4a90fdf6-4) is affected by this issue. I also experimented with different older builds (18.06.02 & all 19.07 versions) which all seem to behave identically. I also tried a more powerful power supply in case this is related to the current consumption but also without success. The only thing which helped so far is artificially reducing the wifi bandwidth using QoS.

1 Like
6

I'm using OpenWrt 19.07.4 r11208-ce6496d796 and I also experience the issues. The wifi network is just disappearing after some hours and only reboot helps

1 Like
7

I have the same issue. Using this: OpenWrt SNAPSHOT, r17247-022d1fe80f
This happens only on heavy traffic via wifi. There is nothing in the logs except
messages like:
mt76_wmac 10300000.wmac: MCU message 08 (seq 5) timed out
....

8

Disabling WMM seems to help? Awaiting resolution to this issue.

9

WMM should be enabled...on both bands.

One potential solution -