I have this occasional error in the kernel log. I'm using a TP-LINK WN722N (AR9271) as USB wifi adapter.
I don't know if it's related but I have had TP-LINK Archer VR200v modem before MT7621.
With Archer VR200v, I was having a problem that my 5GHZ wireless was disappearing by itself. After further investigation, I found out that my KII Pro TV BOX was causing that.
I know that's strange but when I turn off my TV BOX, 5ghz was working fine.
Anyway, can a wireless client cause this error below? My TV BOX has AP6255 wireless chip.
[173121.898851] ------------[ cut here ]------------
[173121.903632] WARNING: CPU: 1 PID: 14 at net/sched/sch_hfsc.c:1400 0x8f3e1d88
[173121.910656] Modules linked in: ath9k_htc ath9k_common pppoe ppp_async ath9k_hw ath pppox ppp_generic nf_conntrack_ipv6 mac80211 iptable_nat ipt_REJECT ipt_MASQUERADE cfg80211 xt_time xt_tcpudp xt_tcpmss xt_statistic xt_state xt_recent xt_nat xt_multiport xt_mark xt_mac xt_limit xt_length xt_hl xt_helper xt_ecn xt_dscp xt_conntrack xt_connmark xt_connlimit xt_connbytes xt_comment xt_TCPMSS xt_REDIRECT xt_LOG xt_HL xt_DSCP xt_CT xt_CLASSIFY uas slhc nf_reject_ipv4 nf_nat_redirect nf_nat_masquerade_ipv4 nf_conntrack_ipv4 nf_nat_ipv4 nf_nat nf_log_ipv4 nf_defrag_ipv6 nf_defrag_ipv4 nf_conntrack_rtcache iptable_mangle iptable_filter ipt_ECN ip_tables crc_ccitt compat sch_cake act_connmark nf_conntrack act_skbedit act_mirred em_u32 cls_u32 cls_tcindex cls_flow cls_route cls_fw sch_tbf sch_htb sch_hfsc
[173121.981155] sch_ingress ip6t_REJECT nf_reject_ipv6 nf_log_ipv6 nf_log_common ip6table_mangle ip6table_filter ip6_tables x_tables ifb tun usb_storage ext4 jbd2 mbcache crc32c_generic mmc_block mtk_sd mmc_core leds_gpio xhci_mtk xhci_plat_hcd xhci_pci xhci_hcd ahci libahci libata sd_mod scsi_mod gpio_button_hotplug usbcore nls_base usb_common
[173122.010173] CPU: 1 PID: 14 Comm: ksoftirqd/1 Tainted: G W 4.9.72 #0
[173122.017626] Stack : 00000000 00000000 80567b4a 00000044 80411ca4 00000000 00000000 80560000
[173122.026098] 8fc5611c 804f9ea7 8048ef74 00000001 0000000e 80563824 00000008 fffffa1e
[173122.034538] 8ef9ecc0 8006ab78 00000001 80560000 80500004 80500008 80493b80 8fc87abc
[173122.042973] 00000003 800a9590 00000008 fffffa1e 8121de20 00000000 00000001 00c87abc
[173122.051413] 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[173122.059846] ...
[173122.062369] Call Trace:
[173122.064921] [<8000f814>] show_stack+0x54/0x88
[173122.069353] [<801e78ac>] dump_stack+0x8c/0xd0
[173122.073782] [<8002adc4>] __warn+0xe4/0x118
[173122.077946] [<8002ae8c>] warn_slowpath_null+0x1c/0x30
[173122.083100] [<8f3e1d88>] 0x8f3e1d88
[173122.086762] ---[ end trace 9cada4149f5b9cc2 ]---