Help debugging wp-login redirect reauth=1 error

I have been running the same configuration on my VPS for a year now. Debian 7 x32 with Apache 2.2, PHP 5.6 and MySQL 5.5. Some things that have changed recently is using https for thea dmin area, but that was over 2 weeks ago (I know https should be all or nothing and is part of my migration plan). I added ipv6 to the server a week ago but had no issues logging in after rebooting the VPS.

After a DNS problem with CloudFlare last night I am now unable to log in to my admin area. Been searching and trying fixes all day, here is a list so far:

Bad credentials still return invalid credentials error

Flushed cookies, used different browsers

Changed salts in wp-config.php

Checked permissions of wp-config.php and whole wordpress directory

Change url to https://sitename (was https://sitename) in option_table of wp_options using MySQL cli

Checked table integrity using mysqlcheck

Renamed plugins folder and restarted, no change

Renamed active theme, same issue when using twenty-fourteen

Removed .htaccess

Funnily enough using the WordPress Android app – which I never use – I can see new post drafts and updates but I cannot enter wp-admin since it redirects me to login

Any help would be greatly appreciated.