Super persistent modem issues

[burntbread]

Hi,

The problem
Certain websites (Facebook, Microsoft Security Essentials, certain forums etc.) will not load on my Macbook (running OS X 10.7) when I am connected to my home Wi-Fi network. The websites in question open on the computer when I use other Wi-Fi networks and other devices report the same issues on my home network so I am certain that there is something wrong with my home Wi-Fi internet connection. I am using an Asus DSL-N10E as a modem that is connected to an Apple Airport Extreme (2013 tower model) for Wi-Fi.

History
This issue first surfaced about a year ago when I couldn't get Windows and security updates on my work PC. After weeks of trying to solve the issue on various forums (documented here, here and here) I began to suspect that my router had been infected and tried connecting to the Internet via a 3G data stick. This worked fine and I was able to get Windows Updates and security software installers. I then went and formatted my computer, reinstalled Windows 7, and got a brand new router. However, the issue persisted. I was then told by a local computer engineer that the problem arose due to viruses and malware coming from the ISP. I couldn't understand how this could be the case, especially since none of my computers were infected but I had no options left and so I changed my ISP and the problem went away.

It is now back!

Questions

1. What is causing this issue? I've run all sorts of test the first time this issue came up (as can be seen from the links above) and they have all come clean. Have my security and privacy been compromised and given that I have been using this computer for the past year do I need to worry about changing all of my passwords etc.?

2. Could this be a BIOS virus/malware?

3. How could I identify the issue and resolve it once and for all?

I am at a complete loss as to what to do next and would really appreciate some help!

 

[ch33zw1z]

Try the network forum.

And, what ISP are you using?

-You can try manually setting the DNS servers to something else

-Try a different modem.

 

[burntbread]

Try the network forum.

And, what ISP are you using?

-You can try manually setting the DNS servers to something else

-Try a different modem.

I'm in India and am using Tata Docomo wired broadband. Prior to this (when the problem was first noticed) I was using BSNL broadband. I've tried using Google's DNS but the issue persists. I did change my modem when the problem first cropped up. This didn't help but, as I've mentioned, changing the ISP did. However, 11 months down the road I'm back to square one.

 

[denis280]

I would check for malware.you are using wifi.are you alone????and can you try direcly no wifi.

 

[burntbread]

The malware checks I did on my work PC when the problem first arose last year came back fine (all the logs are in the links mentioned in my first post). Also, the problem seems to be modem/router/internet related as all devices connected to that particular Wi-Fi network exhibit it. For example, I couldn't get an Apple support page to open on my iPhone yesterday. As I've mentioned, the Macbook in question can connect to these sites on other networks. The network is password protected and I am the only one using it or has access to it since nobody lives in the vicinity.

Strangely, this morning things seemed to be working again and the problem disappeared. However, I feel very uncomfortable not knowing what is up. Could my modem/router have been compromised? If so, what do I do to test this? As I've said before, both the modem and the router are new (different from the ones that exhibited this problem first last year) so I don't know how they could have been infected in the first place.