After upgrading from openwrt-19.07.0-rc2-ar71xx-generic-archer-c7-v5-squashfs-sysupgrade to openwrt-19.07.1-ath79-generic-tplink_archer-c7-v5-squashfs-sysupgrade My 2.4GHz WiFi did not turn on.
I have found and installed openwrt-19.07.2-ath79-generic-tplink_archer-c7-v5-squashfs-sysupgrade and problem with my WiFi is no more.
Just wanted to provide a feedback here for other people that may have similar problem as it is a kind of problem that seems to happen rarely
You could also correct the pci device address im config/wireless manually and it starts to work again. This is a migration issue, beginning with fresh defaults it works out of the box
If you are comnected via cable you could delete the etc/config/wireless file, reboot, take the correct address out to clipboard, restore your wireless config and put the address to radio1/path
I don't remember it because typing on my phone.
Having the same issue with 19.07.1-ath79 on TP-Link TL-WDR3600. I made the mistake not to un-check "keep config" while upgrading. I don't know enough to follow your instructions. Is there is simple way to get 2.4GHz back? Can I rollback and redo upgrade with un-checked "keep config" or something like this?
Thanks in advance for any help.