Unable to login WordPress admin page wp-admin?

Recently, I have a little problem with my WordPress admin login. I can access the wp-admin page with Firefox and Chrome, but not with Internet Explorer. The browser returned a "HTTP 406 Not Acceptable" error. When I clicked more info, it says, "This error (HTTP 406 Not Acceptable) means that Internet Explorer was able to receive information from the website you visited, but the information was not in a format that Internet Explorer can display."

So I contacted my Hostgator support, and found out that my IP was temporarily blocked. They got it fixed within minutes. That's some kind of service! How did that happen... It appears that lately, there is a some kind of global WordPress brute force flood, and I happen to login quite often lately, so my IP got blocked. :)

For more info of this brute force flood, you can visit this Hostgator blog post, or this CloudFlare post. CloudFlare provides a possible explanation of how this could happen:

"One of the concerns of an attack like this is that the attacker is using a relatively weak botnet of home PCs in order to build a much larger botnet of beefy servers in preparation for a future attack. These larger machines can cause much more damage in DDoS attacks because the servers have large network connections and are capable of generating significant amounts of traffic. This is a similar tactic that was used to build the so-called itsoknoproblembro/Brobot botnet which, in the Fall of 2012, was behind the large attacks on US financial institutions."

So if you have also received this HTTP 406 error, contact your hosting support to whitelist your IP.