I have a internet problem. Can somebody help?

[Mark]

Http websites do not work on any browser.
Example: http://uk.yahoo.com/ -> Does not work.
Https websites do work on all browsers.
Example: https://www.paypal.com/uk/webapps/mpp/home -> Does work.

I've tried using my phone and my other laptop. I have the same problem on them as well.

So I believe it is something to do with my internet connection and so something to do with my router.
I tried restarting it, but to no avail.

My router:
Menara ADSL
I've typed in my gateway IP address into the address bar and seeing if I can fix the ports or something from there, but I have no idea what to do and don't want to mess anything up.

Can somebody please help me solve this problem?