WordPress Admin Login "Reauth=1" loop

Hi,

When I try to login to WordPress Admin Panel, it gets redirected to the “reauth=1” page. This happened after the following changes were made at my hosting end, yesterday.

1. Attached my domain to Cloudfare yesterday, and got a DNS change notification today from WordFence

2. Started nginx server in Plesk.

3. I used “Check Security” option in Plesk to secure WordPress

Here is what I tried already, and didn’t fix the problem:

1. Cleared cookies, and browsing data in all browsers.
2. Generate new secret keys from salt, and updated wp-config.php
3. Restored the site from my last VaultPress backup
4. Turned off nginx server and rebooted the server.
5. Detached the domain from Cloudfare (might take a day to take effect.)
6. Disabled *all* Plugins to test
7. Tested withe the default “twenty..” theme. then Reverted back to GeneratePress.

Any suggestions to fix the Admin login issue will be much appreciated.

If I should seek professional help, any pointers on that would be helpful too.

Thanks,