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FS#4065 - WD mynet n750 experiences wifi hw failure with default TX power setting on all OWRT builds #9048

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openwrt-bot opened this issue Oct 6, 2021 · 2 comments
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@openwrt-bot openwrt-bot commented Oct 6, 2021

apassiou:

Devince: WD mynet n750

SW versions: All openwrt builds (latest tried: OpenWrt 21.02.0-rc4, r16256-2d5ee43dc6)

Severity: High, due to difficulty to diagnose (took months of experimentation), and catastrophic outcome for most users (deeming router broken and throwing it away). Moreover the fix should take a few minutes (see below).

Summary: Default Wifi TX strength of 20dbm or higher causes wifi failures within a few weeks. Default value should be changed to 19dbm.

Description:
This has been verified on 3 WD mynet n750 routers. The WD mynet n600 series does not exhibit this problem.

Default setting of WiFi TX power 20dbm on World setting and especially 22db setting on USA setting make the WiFi hardware in these routers unstable. They fail within a timeframe of 1 to 14 days.

Symptom of failure is that while WiFi connection to the router is stable it does not send any traffic to the device. Recovery can be done via power cycling the router or running "wifi off && wifi on" via SSH. This failure appears to be isolated to WiFi hardware as RJ45 connections to the router continue to operate without any issues.

Fix: Set default value of OpenWRT for these routers to 19dbm TX power. Most will never play with this setting and wont know to change it, instead when their wifi fails they will throw away the router as broken. Seeing how most wifi cliets transmit in 14-16dbm range this change should not make any difference on wifi range/strength. So this change should only improve stability and has no downsides.

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@openwrt-bot openwrt-bot commented Oct 20, 2021

apassiou:

Not sure if related but see the following in dmesg:

[797323.112284] ------------[ cut here ]------------
[797323.117144] WARNING: CPU: 0 PID: 7 at backports-5.10.42-1/net/mac80211/rate.c:688 0x8771e77c [mac80211@b9877e6a+0x7d0f0]
[797323.128308] Modules linked in: ath9k ath9k_common pppoe ppp_async iptable_nat ath9k_hw ath xt_state xt_nat xt_conntrack xt_REDIRECT xt_MASQUERADE xt_FLOWOFFLOAD xt_CT pppox ppp_generic nf_nat nf_flow_table_hw nf_flow_table nf_conntrack mac80211 ipt_REJECT cfg80211 xt_time xt_tcpudp xt_multiport xt_mark xt_mac xt_limit xt_comment xt_TCPMSS xt_LOG slhc nf_reject_ipv4 nf_log_ipv4 nf_defrag_ipv6 nf_defrag_ipv4 iptable_mangle iptable_filter ip_tables crc_ccitt compat nf_log_ipv6 nf_log_common ip6table_mangle ip6table_filter ip6_tables ip6t_REJECT x_tables nf_reject_ipv6 fsl_mph_dr_of ehci_platform ehci_fsl ehci_hcd gpio_button_hotplug usbcore nls_base usb_common
[797323.187551] CPU: 0 PID: 7 Comm: ksoftirqd/0 Not tainted 5.4.137 #0
[797323.193925] Stack : 87780000 800b95d8 80660000 805fa440 00000000 00000000 00000000 00000000
[797323.202511] 00000000 00000000 00000000 00000000 00000000 00000001 87c47b20 1d4987dd
[797323.211099] 87c47bb8 00000000 00000000 00000155 00000038 80579e04 00000010 352e342e
[797323.219688] 00000155 0719fa8d 00000000 6b736f66 00000000 87c47b00 00000000 8771e77c
[797323.228269] 00000009 87776a10 875b41fc 80630000 00000010 8031f9d0 00000000 80790000
[797323.236864] ...
[797323.239453] Call Trace:
[797323.239472] [<87780000>] 0x87780000 [ath9k@80f14dff+0x19110]
[797323.247874] [<800b95d8>] 0x800b95d8
[797323.251514] [<80660000>] 0x80660000
[797323.255160] [<80579e04>] 0x80579e04
[797323.258796] [<8771e77c>] 0x8771e77c [mac80211@b9877e6a+0x7d0f0]
[797323.264920] [<8031f9d0>] 0x8031f9d0
[797323.268567] [<87780000>] 0x87780000 [ath9k@80f14dff+0x19110]
[797323.274414] [<80069364>] 0x80069364
[797323.278056] [<8006936c>] 0x8006936c
[797323.281698] [<800821b4>] 0x800821b4
[797323.285350] [<8771e77c>] 0x8771e77c [mac80211@b9877e6a+0x7d0f0]
[797323.291461] [<8008225c>] 0x8008225c
[797323.295110] [<8771e77c>] 0x8771e77c [mac80211@b9877e6a+0x7d0f0]
[797323.301218] [<80660000>] 0x80660000
[797323.304861] [<80660000>] 0x80660000
[797323.308502] [<800c3bfc>] 0x800c3bfc
[797323.312152] [<877895cc>] 0x877895cc [ath9k@80f14dff+0x19110]
[797323.318009] [<8778c928>] 0x8778c928 [ath9k@80f14dff+0x19110]
[797323.323853] [<804936f4>] 0x804936f4
[797323.327519] [<87784400>] 0x87784400 [ath9k@80f14dff+0x19110]
[797323.333368] [<800aba88>] 0x800aba88
[797323.337023] [<87730ccc>] 0x87730ccc [mac80211@b9877e6a+0x7d0f0]
[797323.343144] [<87730e20>] 0x87730e20 [mac80211@b9877e6a+0x7d0f0]
[797323.349257] [<87738b50>] 0x87738b50 [mac80211@b9877e6a+0x7d0f0]
[797323.355377] [<8773a774>] 0x8773a774 [mac80211@b9877e6a+0x7d0f0]
[797323.361482] [<803e0978>] 0x803e0978
[797323.365122] [<800aa724>] 0x800aa724
[797323.368765] [<80660000>] 0x80660000
[797323.372408] [<80660000>] 0x80660000
[797323.376051] [<80085040>] 0x80085040
[797323.379696] [<8057f3b8>] 0x8057f3b8
[797323.383340] [<800a2a30>] 0x800a2a30
[797323.386965] [<800851a4>] 0x800851a4
[797323.390607] [<8057b250>] 0x8057b250
[797323.394250] [<800a2b74>] 0x800a2b74
[797323.397893] [<8009e4ec>] 0x8009e4ec
[797323.401535] [<8057b4c0>] 0x8057b4c0
[797323.405179] [<8009e888>] 0x8009e888
[797323.408822] [<8009e750>] 0x8009e750
[797323.412466] [<8009e750>] 0x8009e750
[797323.416109] [<80064bf8>] 0x80064bf8
[797323.419755]
[797323.421355] ---[ end trace 747c5040e6cbbf70 ]---
[2075814.617335] ------------[ cut here ]------------
[2075814.622300] WARNING: CPU: 0 PID: 0 at backports-5.10.42-1/net/mac80211/rate.c:677 0x8771e750 [mac80211@b9877e6a+0x7d0f0]
[2075814.633526] Modules linked in: ath9k ath9k_common pppoe ppp_async iptable_nat ath9k_hw ath xt_state xt_nat xt_conntrack xt_REDIRECT xt_MASQUERADE xt_FLOWOFFLOAD xt_CT pppox ppp_generic nf_nat nf_flow_table_hw nf_flow_table nf_conntrack mac80211 ipt_REJECT cfg80211 xt_time xt_tcpudp xt_multiport xt_mark xt_mac xt_limit xt_comment xt_TCPMSS xt_LOG slhc nf_reject_ipv4 nf_log_ipv4 nf_defrag_ipv6 nf_defrag_ipv4 iptable_mangle iptable_filter ip_tables crc_ccitt compat nf_log_ipv6 nf_log_common ip6table_mangle ip6table_filter ip6_tables ip6t_REJECT x_tables nf_reject_ipv6 fsl_mph_dr_of ehci_platform ehci_fsl ehci_hcd gpio_button_hotplug usbcore nls_base usb_common
[2075814.692842] CPU: 0 PID: 0 Comm: swapper Tainted: G W 5.4.137 #0
[2075814.700354] Stack : 87780000 800b95d8 80660000 805fa440 00000000 00000000 00000000 00000000
[2075814.709038] 00000000 00000000 00000000 00000000 00000000 00000001 87c0bc30 3f0d8aa1
[2075814.717707] 87c0bcc8 00000000 00000000 0000018b 00000038 80579e04 20202057 20202020
[2075814.726373] 0000018b 947c4606 00000000 000a926a 00000000 87c0bc10 00000000 8771e750
[2075814.735042] 00000009 87776a10 875b81a0 80630000 00000003 8031f9d0 00000000 80790000
[2075814.743710] ...
[2075814.746373] Call Trace:
[2075814.746390] [<87780000>] 0x87780000 [ath9k@80f14dff+0x19110]
[2075814.754985] [<800b95d8>] 0x800b95d8
[2075814.758709] [<80660000>] 0x80660000
[2075814.762434] [<80579e04>] 0x80579e04
[2075814.766171] [<8771e750>] 0x8771e750 [mac80211@b9877e6a+0x7d0f0]
[2075814.772379] [<8031f9d0>] 0x8031f9d0
[2075814.776126] [<87780000>] 0x87780000 [ath9k@80f14dff+0x19110]
[2075814.782060] [<80069364>] 0x80069364
[2075814.785787] [<8006936c>] 0x8006936c
[2075814.789509] [<800821b4>] 0x800821b4
[2075814.793242] [<8771e750>] 0x8771e750 [mac80211@b9877e6a+0x7d0f0]
[2075814.799440] [<8008225c>] 0x8008225c
[2075814.803185] [<8771e750>] 0x8771e750 [mac80211@b9877e6a+0x7d0f0]
[2075814.809401] [<8772e650>] 0x8772e650 [mac80211@b9877e6a+0x7d0f0]
[2075814.815601] [<800c3bfc>] 0x800c3bfc
[2075814.819345] [<877895cc>] 0x877895cc [ath9k@80f14dff+0x19110]
[2075814.825292] [<8778c928>] 0x8778c928 [ath9k@80f14dff+0x19110]
[2075814.831242] [<87784400>] 0x87784400 [ath9k@80f14dff+0x19110]
[2075814.837190] [<87730ccc>] 0x87730ccc [mac80211@b9877e6a+0x7d0f0]
[2075814.843402] [<87730e20>] 0x87730e20 [mac80211@b9877e6a+0x7d0f0]
[2075814.849621] [<87738b50>] 0x87738b50 [mac80211@b9877e6a+0x7d0f0]
[2075814.855832] [<8773a774>] 0x8773a774 [mac80211@b9877e6a+0x7d0f0]
[2075814.862043] [<87784c28>] 0x87784c28 [ath9k@80f14dff+0x19110]
[2075814.867974] [<80660000>] 0x80660000
[2075814.871701] [<80660000>] 0x80660000
[2075814.875424] [<80085040>] 0x80085040
[2075814.879147] [<800ba4d0>] 0x800ba4d0
[2075814.882878] [<8057f3b8>] 0x8057f3b8
[2075814.886608] [<800bf060>] 0x800bf060
[2075814.890331] [<802bf200>] 0x802bf200
[2075814.894064] [<80064f78>] 0x80064f78
[2075814.897790]
[2075814.899477] ---[ end trace 747c5040e6cbbf71 ]---

@ynezz
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@ynezz ynezz commented Feb 26, 2022

Continue tracking this via #5078

@ynezz ynezz closed this as completed Feb 26, 2022
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