phpmyadmin net ::关于AJAX操作的ERR_CONNECTION_RESET

phpmyadmin works fine. It doesn't work when I try to perform a lot of AJAX operations such as clicking "edit" on a record. Even if I try to run a SQL->SELECT->Go I have problems.

I'm getting this error from my chrome dev console:

net::ERR_CONNECTION_RESET

I tried with different db/users/full privileges and with different browsers. I did not found a single post about this on Google.

I have full access to the server, which is a Debian server (Apache/2.4.10 libmysql - 5.5.47). PHP memory limit is very high.

No errors at all on APACHE error.log.

What can I do to identify the problem?