Nginx – Can’t access nginx from outside server

Here I am again with yet again another strange error with nginx.

I am running a server with debian and nginx as webserver. Everything was working fine until it suddenly stopped accepting connections from outside the server. I can't access the website from any browser (throughs ERR_CONNECTION_TIMED_OUT), I can't connect using telnet to the server IP, server IP and port 80 or 443… but I can access through the port 22, so SSH and FTP are working.

If through SSH I do curl IP it shows the content of my HTML.

As I said, everything was working before, it was all of a sudden, without doing any change on the server.

Also nginx it's running and not showing any error.

I am totally lost to be honest. Any ideas about why this happens and how to solve it?

EDIT:

Here is the access.log. It doesn't show any of the times I try to access the website from any browser.

94.23.253.89 - - [19/Nov/2015:00:47:57 +0100] "GET / HTTP/1.1" 200 18 "-" "curl/7.38.0"
94.23.253.89 - - [19/Nov/2015:00:48:16 +0100] "GET / HTTP/1.1" 200 18 "-" "curl/7.38.0"
94.23.253.89 - - [19/Nov/2015:00:48:23 +0100] "GET / HTTP/1.1" 200 5194 "-" "curl/7.38.0"

And here is the result of netsat -ltnp

tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      940/nginx -g daemon
tcp6       0      0 :::80                   :::*                    LISTEN      940/nginx -g daemon

EDIT 2 I forgot to mention that I am also running iRedMail (dovecot, postfix, fail2ban)