Wacky internet network issues.

[Dareus]

Hey, I was hoping you guys might be able to help me with a problem I've been having recently. In my house there are 4 computers, and up to a few days ago they all were able to connect to the internet without issue. However, last week my dad's pc got some virus and he had to get it cleaned professionally. After he got it back our internet network became completely fucked up. If his computer is able to access the internet, the 3 others will be unable to connect. vice versa, if his is unable to connect, that means that the other 3 will be able to use the internet without issue.

At first i thought it might be a firewall issue on his PC (which is the one the modem connects to) but even with the firewalls off the internet still won't work correctly. I'm not sure where to go from here to fix the issue and was hoping someone may have had to deal with this before and could give me some new ideas. Any help would be awesome as this has begun to annoy me to no end. Thanks!

[Dareus]

As I feared, I must be screwed. Anyone know if perhaps having a different IP on each PC could be fucking it up? I assume it doesn't but I'm pretty fail with computers.

[Stee]

That's a odd problem to have and each computer is suppose to have its own IP so your ok there.

If I were you I would try first clearing the connection/wireless profiles in your dads computer and see if that helps or maybe reset your router or something.

And what do you mean that other computers can't connect? is it a error message or does the connection just not show up?

[Dareus]

I'll try clearing all the connections on his PC and see if that fixes it. I've already reset the router a bunch of times but to little effect. And what I mean by "can't connect" is that if his computer is able to go online, all the other computers in the house will still be connected to the network, but will not connect to the internet. reversly if the other computers in the house are able to connect to the internet it will only be his who shows no connection.

I'm not sure if it is this way on all computers but I use Vista and when I look at my connection settings while able to connect to the internet it looks like this:
This computer-------network-------internet

But when my dad is able to go online on his pc, my connection settings look like this:

This computer-----network---X---internet(Grayed out)


Thanks for the help Stee!

[Jmeat]

I work in IT and awhile back there was a crappy trojan going around that would infect a PC on the network and turn it into a DHCP/DNS server. It would force computers on our network to look to the infected computer instead of the true DNS servers causing behavior similar to what you are describing.

A way to test this would be to obtain your ISP's DNS servers and set them manually and also set a static IP that matches what your router is handing out.

Kind of a long shot, but worth a shot.