Note: I've seen forum posts with people having similar issues to this, and have attempted to use any and all solutions covering various potential issues found, all in vain. Re-posting in hopes someone has a new/more up-to-date solution or greater knowledge of the problem since those posts were made.
Background: "Bricked" my Archer C7 v3 router. Was caught in a 5-second reboot cycle; couldn't utilize TFTP method (server on 0.66) to fix, so I purchased a PL2303 USB-Serial adapter and was able to successfully load both the original TP-Link factory firmware and the C7 v2/3 build of 18.06.5 using the following commands per the wiki:
tftp 0x81000000 [name of your firmware file].bin erase 0x9f020000 +f80000 cp.b 0x81000000 0x9f020000 0xf80000 reset
Problem: After getting an IP4 address via DHCP and successfully connecting to the router via Luci web interface, I am not able to either 1) login via root/[blank] or 2) set the root password using the "Go to password configuration..." button. In both cases, the page just reloads. If I enter anything besides [blank] for the pw, the page also just reloads — no error message is returned.
At the same time, I can login successfully via SSH with root/[blank], and from there set a root password. After that, when attempting to login via the web interface, an incorrect pw will return an error message; the correct password will once again just cause the page to reload with no login.
Solutions Attempted: I've read about and checked my setup for the following potential issues:
RCPD not running
Wrong permissions on RCPD config file
RCPD config missing the following:
config login option username 'root' option password '$p$root' list read '*' list write '*'
Lua not properly talking to ubus
Logins via ubus not working
Incorrect permissions on /etc/shadow file
Corrupted /etc/shadow file
Browser cache/cookies issues
I've worked through all of these, and none seem to be a problem/are set correctly/aren't missing/etc. So if by chance anyone can shed some new light on this, I would be extremely grateful. Could something else essential have been lost during the original bricking, or when the flash was wiped via serial command? Is this something possibly specific to the v3 model of the C7?
Thanks in advance.