Archer C7 2.4 GHz wireless dies in 24~48 hours

Installing and Using OpenWrt Network and Wireless Configuration
305

Solved on my CPE 210 (v2 and v3) by changing the wireless config:
(need to add the option "ldpc" because by default it is active, to disable the feature)

/etc/config/wireless:

config wifi-device 'radio0'
...
option ldpc '0'

2 Likes
306

Is this option valid for the ath10k-ct or the non-ct driver?

307

Doesnt affect 10k driver as it's 9k for 2.4Ghz

1 Like
308

Right, and does the option also help for Archer C7v2 ?

309

It should do, the C7v2 uses the same ath9k driver for the 2.4GHz radio.

1 Like
310

This is my Archer C7v5 output. Running OpenWrt 21.02.3 here. I did not specify the ldpc option in my /etc/config/wireless config.

grep ht_ca /tmp/run/hostapd-phy*.conf
/tmp/run/hostapd-phy0.conf:ht_capab=[HT40+][LDPC][SHORT-GI-20][SHORT-GI-40][TX-STBC][RX-STBC1][MAX-AMSDU-7935][DSSS_CCK-40]
/tmp/run/hostapd-phy0.conf:vht_capab=[RXLDPC][SHORT-GI-80][TX-STBC-2BY1][RX-ANTENNA-PATTERN][TX-ANTENNA-PATTERN][RX-STBC-1][MAX-MPDU-11454][MAX-A-MPDU-LEN-EXP7]
/tmp/run/hostapd-phy1.conf:ht_capab=[HT40+][SHORT-GI-20][SHORT-GI-40][TX-STBC][RX-STBC1][DSSS_CCK-40]

I think radio1/phy1 is the 2.4 GHz WiFi.

Ran an iperf3 test multiple times, here are the results:

  • 2.4 GHz WiFi without "option ldpc '0'" - ~70 Mbit/sec
  • 2.4 GHz WiFi with "option ldpc '0'" - ~70 Mbit/sec
  • 5 GHz WiFi - ~ 138 MBit/sec

I've made sure to restart the phy radio after adding/removing the option ldpc line. It didn't make any difference. I suspect LDPC is already turned off by OpenWrt 21.02.3's defaults because the "grep ht_ca" above does indicate this.

311

Interesting... C7v5 does NOT have LDPC by default.

I ran the grep ht_ca command on a TP-Link Archer C7v2 and indeed, there is LDPC and it's on by default.

grep ht_ca /tmp/run/hostapd-phy*.conf
/tmp/run/hostapd-phy0.conf:ht_capab=[HT40+][LDPC][SHORT-GI-20][SHORT-GI-40][TX-STBC][RX-STBC1][MAX-AMSDU-7935][DSSS_CCK-40]
/tmp/run/hostapd-phy0.conf:vht_capab=[RXLDPC][SHORT-GI-80][TX-STBC-2BY1][RX-ANTENNA-PATTERN][TX-ANTENNA-PATTERN][RX-STBC-1][MAX-MPDU-11454][MAX-A-MPDU-LEN-EXP7]
/tmp/run/hostapd-phy1.conf:ht_capab=[HT40+][LDPC][SHORT-GI-20][SHORT-GI-40][TX-STBC][RX-STBC1][DSSS_CCK-40]

Disabling LDPC on C7v2 did not change measured performance via iperf3.

After some more tests about bufferbloat and latency, my latency is higher with LDPC enabled. So I'd decide to go with LDPC disabled on my Archer C7 v2 units.

Sample config for TP-Link Archer C7v5 and C7v2 devices for the 2.4 GHz WiFi radio1: https://github.com/Catfriend1/openwrt-presence/blob/master/scripts/wifimgr/radio-iface/20-tplink-archer-c7v5-radio1

1 Like
312

In my tests, applying the following two patches solves the problem.

https://patchwork.kernel.org/project/linux-wireless/patch/20161117083614.19188-1-sven.eckelmann@open-mesh.com/

https://patchwork.kernel.org/project/linux-wireless/patch/20161117083614.19188-2-sven.eckelmann@open-mesh.com/

3 Likes
313

To get my 2.4 GHz to work I needed to disable LDPC otherwise it would not properly enable.
Also before the upgrade to 23.05 I got the obnoxious device not found error.

2 Likes
314

I was facing with the issue described in this post after having upgraded OpenWRT in my Archer C7. I would see my Shelly or Meross devices being offline on a random basis every few days.
After disabling LDPC I can I have not experienced this issue for the past several weeks now. Thank you for posting this solution.