This is a recent problem I've been having.

My site can be accessed from almost everywhere else except from my home IP, where I do most of my editing/updating, etc. I've tested my connection from my school's network, a friend's connection from out of state (multiple states), and through a tethered connection with my friend's Android. It works in all those cases, both viewing, accessing the cPanel, and using FTP.

Here's the problem that happens to me when I try to view it from my home IP:

• The page times out in Firefox, IE, and Chrome.
• Using the cmd, I ran tracert and ping, both as failed attempts. Log here.
• downforeveryoneorjustme.com says my site is up. So do the other site checkers.
• I can't access my cPanel or FTP accounts.
• I can't access the host site. (I use perfectz.info for hosting, and I can't access their site either.)

System settings:

• No firewall enabled.
• Ports are seemingly properly forwarded. (e.g. The ports are open in the router settings, and are open everywhere else.)
• I have an email forwarder set up from the cPanel that works just fine. (i.e. I can receive emails sent to that address.

If any other information is needed, I'll do my best to provide it.

UPDATE

@ilhan: I use two things:

1) The site cPanel from in-browser.

2) Dreamweaver CS5 FTP.

@Matthias: I tested both, and it passes the dual stack with a 10/10. What should I do then?