5g WiFi stopped working completely

[lockheed]

I have a D-Link DIR-2660 which has been running OpenWRT 23.05.3 happily for a long time. So I saved my config and upgraded to 23.05.5 (keeping config). But upon reboot, 5G WiFi was not working. It also could not be started from Luci. So I had to first enable it from shell
ip link set phy1-ap0 up
and only then it would show you as enabled in Luci. However, there would still be no wifi generated.

So I played around with settings, changing Channels from previous 48 to some lower ones, or even Auto – nothing helped. Changing width form 80Hz down also did nothing. Basically, 5g WiFi will not start. While 2.5g works just fine.

In addition, upon every restart, the 5G ration has to be manually enabled from shell, otherwise it stays disabled.

Things I tried:

1. Upgrading to latest snapshots,
2. Downgrading to the previously perfectly working 23.05.3
3. Resetting configuration and resting from backup.

Nothing helped. Both issues remain.

[egc]

What if you just reset to defaults and do not restore a previous backup but just make the minimal necessary changes e.g. channel number , SSID, encryption 'psk2' and password)?

[zekica]

Can you show dmesg and system log? MT7615 should work fine.

[lockheed]

Here's dmesg: https://pastebin.com/raw/XQu85jST

[ 12.067380] ieee80211 phy0: Selected rate control algorithm 'minstrel_ht'
[ 12.073560] pci 0000:00:01.0: enabling device (0006 -> 0007)
[ 12.085004] mt7615e 0000:02:00.0: enabling device (0000 -> 0002)
[ 12.097334] mt7615e 0000:01:00.0: HW/SW Version: 0x8a108a10, Build Time: 20180518100604a
[ 12.097334]
[ 12.114279] ieee80211 phy1: Selected rate control algorithm 'minstrel_ht'
[ 12.116447] ieee80211 phy1: copying sband (band 1) due to VHT EXT NSS BW flag
[ 12.170006] mt7615e 0000:02:00.0: HW/SW Version: 0x8a108a10, Build Time: 20180518100604a

As evident, 5g device (phy1) isn't being enabled for some reason.

logread only show messages about 2.4g ration. Nothing about 5g.

@egc I can't do that as I am remote atm, and if I reset the device I won't be able to access it.

[lockheed]

Well, it was some untraceable bug. I ditched saved config and re-did the configuration from scratch. The problem seems to be gone.