For those who bump into this thread with login issues, a summary:
Some ppl can't log in even though they know the password is correct. Broadly I see two situations:
- they get a
password incorrect
- this might be due to RPCD config or shadow permissions
- they get nothing (the page just reloads. If they give a WRONG password, they get the
password incorrect
message) This seems cookie related
Here are some solutions to try.
RPCD
Might be a rpcd
issue. Check if /etc/config/rpcd
has this:
config login
option username 'root'
option password '$p$root'
list read '*'
list write '*'
If not, edit, restart rcpd
with /etc/init.d/rpcd restart
shadow
Make sure /etc/shadow
has the right permissions: chmod 644 /etc/shadow
re-set the password
Change (or re-enter) your pw with passwd
then restart uhttpd
with /etc/init.d/uhttpd restart
uhttpd config
The thread starter had an empty /etc/config/uhttpd
- and copied it over from default, then had to fix shadow:
rm /etc/shadow && cp /overlay/upper/etc/shadow /etc && passwd
Note the discussion, though, this conversation isn't over yet it seems.
Cookies
Delete cookies from the domain. Be thorough - my cookie deletion tool in Chrome claims there are no cookies, but when I look into the cookie store I can still find them with a search on the router IP address and have to manually remove them. THEN login works again.
If you tried it all and no success - I guess you'll have to ask here or create a new conversation 
Good luck!