After updating I changed some settings in my 5 Ghz network and it stopped working at all. I tried deleting network and creating blank from scratch, without chaning any settings, rebooted, etc, no luck. After downgrading to 19.07.3 it worked immediately.
I don't know what log is needed but here I copied after enabling that network. I googled that error and only found referenced from 2 year old reports.
Sat Sep 26 20:13:57 2020 kern.info kernel: [ 416.330398] mtk_soc_eth 1e100000.ethernet eth0: port 4 link down
Sat Sep 26 20:14:04 2020 daemon.info pppd[1461]: No response to 5 echo-requests
Sat Sep 26 20:14:04 2020 daemon.notice pppd[1461]: Serial link appears to be disconnected.
Sat Sep 26 20:14:04 2020 daemon.info pppd[1461]: Connect time 6.5 minutes.
Sat Sep 26 20:14:04 2020 daemon.info pppd[1461]: Sent 1364355 bytes, received 10529014 bytes.
Sat Sep 26 20:14:04 2020 daemon.notice netifd: Network device 'pppoe-wan' link is down
Sat Sep 26 20:14:04 2020 daemon.notice netifd: Interface 'wan' has lost the connection
Sat Sep 26 20:14:04 2020 daemon.info dnsmasq[2033]: reading /tmp/resolv.conf.auto
Sat Sep 26 20:14:04 2020 daemon.info dnsmasq[2033]: using local addresses only for domain test
Sat Sep 26 20:14:04 2020 daemon.info dnsmasq[2033]: using local addresses only for domain onion
Sat Sep 26 20:14:04 2020 daemon.info dnsmasq[2033]: using local addresses only for domain localhost
Sat Sep 26 20:14:04 2020 daemon.info dnsmasq[2033]: using local addresses only for domain local
Sat Sep 26 20:14:04 2020 daemon.info dnsmasq[2033]: using local addresses only for domain invalid
Sat Sep 26 20:14:04 2020 daemon.info dnsmasq[2033]: using local addresses only for domain bind
Sat Sep 26 20:14:04 2020 daemon.info dnsmasq[2033]: using local addresses only for domain lan
Sat Sep 26 20:14:04 2020 daemon.info dnsmasq[2033]: using nameserver 8.8.8.8#53
Sat Sep 26 20:14:10 2020 daemon.notice pppd[1461]: Connection terminated.
Sat Sep 26 20:14:10 2020 daemon.info pppd[1461]: Sent PADT
Sat Sep 26 20:14:10 2020 daemon.notice pppd[1461]: Modem hangup
Sat Sep 26 20:14:10 2020 daemon.info pppd[1461]: Exit.
Sat Sep 26 20:14:10 2020 daemon.notice netifd: Interface 'wan' is now down
Sat Sep 26 20:14:10 2020 daemon.notice netifd: Interface 'wan' is setting up now
Sat Sep 26 20:14:10 2020 kern.info kernel: [ 429.568123] mtk_soc_eth 1e100000.ethernet eth0: port 4 link up
Sat Sep 26 20:14:10 2020 daemon.err insmod: module is already loaded - slhc
Sat Sep 26 20:14:10 2020 daemon.err insmod: module is already loaded - ppp_generic
Sat Sep 26 20:14:10 2020 daemon.err insmod: module is already loaded - pppox
Sat Sep 26 20:14:10 2020 daemon.err insmod: module is already loaded - pppoe
Sat Sep 26 20:14:10 2020 daemon.info pppd[3931]: Plugin rp-pppoe.so loaded.
Sat Sep 26 20:14:10 2020 daemon.info pppd[3931]: RP-PPPoE plugin version 3.8p compiled against pppd 2.4.7
Sat Sep 26 20:14:10 2020 daemon.notice pppd[3931]: pppd 2.4.7 started by root, uid 0
Sat Sep 26 20:14:15 2020 daemon.info pppd[3931]: PPP session is 24277
Sat Sep 26 20:14:15 2020 daemon.warn pppd[3931]: Connected to 44:6a:2e:fa:dc:67 via interface eth0.2
Sat Sep 26 20:14:15 2020 kern.info kernel: [ 434.823328] pppoe-wan: renamed from ppp0
Sat Sep 26 20:14:16 2020 daemon.info pppd[3931]: Renamed interface ppp0 to pppoe-wan
Sat Sep 26 20:14:16 2020 daemon.info pppd[3931]: Using interface pppoe-wan
Sat Sep 26 20:14:16 2020 daemon.notice pppd[3931]: Connect: pppoe-wan <--> eth0.2
Sat Sep 26 20:14:16 2020 daemon.info pppd[3931]: CHAP authentication succeeded: Authentication success,Welcome!
Sat Sep 26 20:14:16 2020 daemon.notice pppd[3931]: CHAP authentication succeeded
Sat Sep 26 20:14:16 2020 daemon.notice pppd[3931]: peer from calling number 44:6A:2E:FA:DC:67 authorized
Sat Sep 26 20:14:16 2020 daemon.notice pppd[3931]: local IP address 95.72.236.77
Sat Sep 26 20:14:16 2020 daemon.notice pppd[3931]: remote IP address 213.140.228.141
Sat Sep 26 20:14:16 2020 daemon.notice pppd[3931]: primary DNS address 213.140.228.190
Sat Sep 26 20:14:16 2020 daemon.notice pppd[3931]: secondary DNS address 213.140.228.30
Sat Sep 26 20:14:16 2020 daemon.notice netifd: Network device 'pppoe-wan' link is up
Sat Sep 26 20:14:16 2020 daemon.notice netifd: Interface 'wan' is now up
Sat Sep 26 20:14:16 2020 daemon.info dnsmasq[2033]: reading /tmp/resolv.conf.auto
Sat Sep 26 20:14:16 2020 daemon.info dnsmasq[2033]: using local addresses only for domain test
Sat Sep 26 20:14:16 2020 daemon.info dnsmasq[2033]: using local addresses only for domain onion
Sat Sep 26 20:14:16 2020 daemon.info dnsmasq[2033]: using local addresses only for domain localhost
Sat Sep 26 20:14:16 2020 daemon.info dnsmasq[2033]: using local addresses only for domain local
Sat Sep 26 20:14:16 2020 daemon.info dnsmasq[2033]: using local addresses only for domain invalid
Sat Sep 26 20:14:16 2020 daemon.info dnsmasq[2033]: using local addresses only for domain bind
Sat Sep 26 20:14:16 2020 daemon.info dnsmasq[2033]: using local addresses only for domain lan
Sat Sep 26 20:14:16 2020 daemon.info dnsmasq[2033]: using nameserver 8.8.8.8#53
Sat Sep 26 20:14:16 2020 daemon.info dnsmasq[2033]: using nameserver 213.140.228.190#53
Sat Sep 26 20:14:16 2020 daemon.info dnsmasq[2033]: using nameserver 213.140.228.30#53
Sat Sep 26 20:14:16 2020 user.notice firewall: Reloading firewall due to ifup of wan (pppoe-wan)
Sat Sep 26 20:16:37 2020 user.notice mac80211: Failed command: iw phy phy1 set antenna 0xffffffff 0xffffffff
Sat Sep 26 20:16:37 2020 daemon.notice netifd: radio1 (4280): command failed: Not supported (-122)
Sat Sep 26 20:16:37 2020 user.notice mac80211: Failed command: iw phy phy1 set distance 0
Sat Sep 26 20:16:38 2020 daemon.err hostapd: Configuration file: /var/run/hostapd-phy1.conf
Sat Sep 26 20:16:38 2020 kern.info kernel: [ 576.886348] IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready
Sat Sep 26 20:16:38 2020 daemon.notice hostapd: wlan1: INTERFACE-ENABLED
Sat Sep 26 20:16:38 2020 daemon.notice hostapd: wlan1: INTERFACE-DISABLED
Sat Sep 26 20:16:38 2020 daemon.err hostapd: nl80211: Could not configure driver mode
Sat Sep 26 20:16:38 2020 daemon.notice hostapd: nl80211: deinit ifname=wlan1 disabled_11b_rates=0
Sat Sep 26 20:16:38 2020 daemon.err hostapd: nl80211 driver initialization failed.
Sat Sep 26 20:16:38 2020 daemon.notice hostapd: wlan1: interface state UNINITIALIZED->DISABLED
Sat Sep 26 20:16:38 2020 daemon.notice hostapd: wlan1: AP-DISABLED
Sat Sep 26 20:16:38 2020 daemon.notice hostapd: wlan1: CTRL-EVENT-TERMINATING
Sat Sep 26 20:16:38 2020 daemon.err hostapd: hostapd_free_hapd_data: Interface wlan1 wasn't started
Sat Sep 26 20:16:38 2020 daemon.notice netifd: radio1 (4280): cat: can't open '/var/run/wifi-phy1.pid': No such file or directory
Sat Sep 26 20:16:38 2020 daemon.notice netifd: radio1 (4280): WARNING (wireless_add_process): executable path /usr/sbin/wpad does not match process path (/proc/exe)
Sat Sep 26 20:16:38 2020 daemon.notice netifd: radio1 (4280): Command failed: Invalid argument
Sat Sep 26 20:16:38 2020 daemon.notice netifd: radio1 (4280): Device setup failed: HOSTAPD_START_FAILED
Sat Sep 26 20:16:55 2020 user.notice mac80211: Failed command: iw phy phy1 set antenna 0xffffffff 0xffffffff
Sat Sep 26 20:16:55 2020 daemon.notice netifd: radio1 (4514): command failed: Not supported (-122)
Sat Sep 26 20:16:55 2020 user.notice mac80211: Failed command: iw phy phy1 set distance 0
Sat Sep 26 20:16:55 2020 daemon.err hostapd: Configuration file: /var/run/hostapd-phy1.conf
Sat Sep 26 20:16:55 2020 kern.info kernel: [ 594.270890] IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready
Sat Sep 26 20:16:55 2020 daemon.notice hostapd: wlan1: INTERFACE-ENABLED
Sat Sep 26 20:16:55 2020 daemon.notice hostapd: wlan1: INTERFACE-DISABLED
Sat Sep 26 20:16:55 2020 daemon.err hostapd: nl80211: Could not configure driver mode
Sat Sep 26 20:16:55 2020 daemon.notice hostapd: nl80211: deinit ifname=wlan1 disabled_11b_rates=0
Sat Sep 26 20:16:55 2020 daemon.err hostapd: nl80211 driver initialization failed.
Sat Sep 26 20:16:55 2020 daemon.notice hostapd: wlan1: interface state UNINITIALIZED->DISABLED
Sat Sep 26 20:16:55 2020 daemon.notice hostapd: wlan1: AP-DISABLED
Sat Sep 26 20:16:55 2020 daemon.notice hostapd: wlan1: CTRL-EVENT-TERMINATING
Sat Sep 26 20:16:55 2020 daemon.err hostapd: hostapd_free_hapd_data: Interface wlan1 wasn't started
Sat Sep 26 20:16:55 2020 daemon.notice netifd: radio1 (4514): cat: can't open '/var/run/wifi-phy1.pid': No such file or directory
Sat Sep 26 20:16:55 2020 daemon.notice netifd: radio1 (4514): WARNING (wireless_add_process): executable path /usr/sbin/wpad does not match process path (/proc/exe)
Sat Sep 26 20:16:55 2020 daemon.notice netifd: radio1 (4514): Command failed: Invalid argument
Sat Sep 26 20:16:55 2020 daemon.notice netifd: radio1 (4514): Device setup failed: HOSTAPD_START_FAILED
Sat Sep 26 20:17:31 2020 user.notice mac80211: Failed command: iw phy phy1 set antenna 0xffffffff 0xffffffff
Sat Sep 26 20:17:31 2020 daemon.notice netifd: radio1 (4731): command failed: Not supported (-122)
Sat Sep 26 20:17:31 2020 user.notice mac80211: Failed command: iw phy phy1 set distance 0
Sat Sep 26 20:17:31 2020 daemon.err hostapd: Configuration file: /var/run/hostapd-phy1.conf
Sat Sep 26 20:17:31 2020 kern.info kernel: [ 630.096732] IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready
Sat Sep 26 20:17:31 2020 daemon.notice hostapd: wlan1: INTERFACE-ENABLED
Sat Sep 26 20:17:31 2020 daemon.notice hostapd: wlan1: INTERFACE-DISABLED
Sat Sep 26 20:17:31 2020 daemon.err hostapd: nl80211: Could not configure driver mode
Sat Sep 26 20:17:31 2020 daemon.notice hostapd: nl80211: deinit ifname=wlan1 disabled_11b_rates=0
Sat Sep 26 20:17:31 2020 daemon.err hostapd: nl80211 driver initialization failed.
Sat Sep 26 20:17:31 2020 daemon.notice hostapd: wlan1: interface state UNINITIALIZED->DISABLED
Sat Sep 26 20:17:31 2020 daemon.notice hostapd: wlan1: AP-DISABLED
Sat Sep 26 20:17:31 2020 daemon.notice hostapd: wlan1: CTRL-EVENT-TERMINATING
Sat Sep 26 20:17:31 2020 daemon.err hostapd: hostapd_free_hapd_data: Interface wlan1 wasn't started
Sat Sep 26 20:17:31 2020 daemon.notice netifd: radio1 (4731): cat: can't open '/var/run/wifi-phy1.pid': No such file or directory
Sat Sep 26 20:17:31 2020 daemon.notice netifd: radio1 (4731): WARNING (wireless_add_process): executable path /usr/sbin/wpad does not match process path (/proc/exe)
Sat Sep 26 20:17:31 2020 daemon.notice netifd: radio1 (4731): Command failed: Invalid argument
Sat Sep 26 20:17:31 2020 daemon.notice netifd: radio1 (4731): Device setup failed: HOSTAPD_START_FAILED
Sat Sep 26 20:17:54 2020 user.notice mac80211: Failed command: iw phy phy1 set antenna 0xffffffff 0xffffffff
Sat Sep 26 20:17:54 2020 daemon.notice netifd: radio1 (4942): command failed: Not supported (-122)
Sat Sep 26 20:17:54 2020 user.notice mac80211: Failed command: iw phy phy1 set distance 0
Sat Sep 26 20:17:54 2020 daemon.err hostapd: Configuration file: /var/run/hostapd-phy1.conf
Sat Sep 26 20:17:54 2020 kern.info kernel: [ 653.497961] IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready
Sat Sep 26 20:17:54 2020 daemon.notice hostapd: wlan1: INTERFACE-ENABLED
Sat Sep 26 20:17:54 2020 daemon.notice hostapd: wlan1: INTERFACE-DISABLED
Sat Sep 26 20:17:54 2020 daemon.err hostapd: nl80211: Could not configure driver mode
Sat Sep 26 20:17:54 2020 daemon.notice hostapd: nl80211: deinit ifname=wlan1 disabled_11b_rates=0
Sat Sep 26 20:17:54 2020 daemon.err hostapd: nl80211 driver initialization failed.
Sat Sep 26 20:17:54 2020 daemon.notice hostapd: wlan1: interface state UNINITIALIZED->DISABLED
Sat Sep 26 20:17:54 2020 daemon.notice hostapd: wlan1: AP-DISABLED
Sat Sep 26 20:17:54 2020 daemon.notice hostapd: wlan1: CTRL-EVENT-TERMINATING
Sat Sep 26 20:17:54 2020 daemon.err hostapd: hostapd_free_hapd_data: Interface wlan1 wasn't started
Sat Sep 26 20:17:54 2020 daemon.notice netifd: radio1 (4942): cat: can't open '/var/run/wifi-phy1.pid': No such file or directory
Sat Sep 26 20:17:54 2020 daemon.notice netifd: radio1 (4942): WARNING (wireless_add_process): executable path /usr/sbin/wpad does not match process path (/proc/exe)
Sat Sep 26 20:17:54 2020 daemon.notice netifd: radio1 (4942): Command failed: Invalid argument
Sat Sep 26 20:17:54 2020 daemon.notice netifd: radio1 (4942): Device setup failed: HOSTAPD_START_FAILED
Sat Sep 26 20:20:19 2020 user.notice mac80211: Failed command: iw phy phy1 set antenna 0xffffffff 0xffffffff
Sat Sep 26 20:20:19 2020 daemon.notice netifd: radio1 (5165): command failed: Not supported (-122)
Sat Sep 26 20:20:19 2020 user.notice mac80211: Failed command: iw phy phy1 set distance 0
Sat Sep 26 20:20:19 2020 daemon.err hostapd: Configuration file: /var/run/hostapd-phy1.conf
Sat Sep 26 20:20:19 2020 kern.info kernel: [ 798.494933] IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready
Sat Sep 26 20:20:19 2020 daemon.notice hostapd: wlan1: INTERFACE-ENABLED
Sat Sep 26 20:20:19 2020 daemon.notice hostapd: wlan1: INTERFACE-DISABLED
Sat Sep 26 20:20:19 2020 daemon.err hostapd: nl80211: Could not configure driver mode
Sat Sep 26 20:20:19 2020 daemon.notice hostapd: nl80211: deinit ifname=wlan1 disabled_11b_rates=0
Sat Sep 26 20:20:19 2020 daemon.err hostapd: nl80211 driver initialization failed.
Sat Sep 26 20:20:19 2020 daemon.notice hostapd: wlan1: interface state UNINITIALIZED->DISABLED
Sat Sep 26 20:20:19 2020 daemon.notice hostapd: wlan1: AP-DISABLED
Sat Sep 26 20:20:19 2020 daemon.notice hostapd: wlan1: CTRL-EVENT-TERMINATING
Sat Sep 26 20:20:19 2020 daemon.err hostapd: hostapd_free_hapd_data: Interface wlan1 wasn't started
Sat Sep 26 20:20:19 2020 daemon.notice netifd: radio1 (5165): cat: can't open '/var/run/wifi-phy1.pid': No such file or directory
Sat Sep 26 20:20:19 2020 daemon.notice netifd: radio1 (5165): WARNING (wireless_add_process): executable path /usr/sbin/wpad does not match process path (/proc/exe)
Sat Sep 26 20:20:19 2020 daemon.notice netifd: radio1 (5165): Command failed: Invalid argument
Sat Sep 26 20:20:19 2020 daemon.notice netifd: radio1 (5165): Device setup failed: HOSTAPD_START_FAILED
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