Internet Connection Dies As Soon As A New Computer Is Added To The Network.

Can someone help me diagnose this? I'm completely stumped. I have no clue what to look for, and I have no clue of what could be causing this.

Basically, the network in my house is a very little bit complex. We have three computers connected to the modem via DSL, and we have a wireless router connected to the modem via DSL too (we use wireless internet frequently, but our desktop computers have no wireless cards, so they are cabled instead). The DSL cable that comes to my room my room is later connected to a hub, and this hub gives wireless internet to my desktop computer, my laptop, and my PS3.

I said all that because I'm not sure if a setup like this could be killing my internet everytime another computer is turned on. My internet works wonderfully when I am the only one using it (or when cellphones are using it and such), but the moment another computer is turned on and connected to the internet, wired or wireless, it takes down the whole network.

It's annoying, and I have no idea of what could be happening, what to google for, or what I should configure. Any help will be appreciated. I have full access to the modem and router if that helps you help me.
Thanks to anyone who can help me with this.

Ren of Heavens, here's a drawing:



This is really embarrassing now that I think of it.

The modem we have is a very old Zoom X3 modem. It's the one provided to us by our internet provider and sadly we can't upgrade or change it unless it starts malfunctioning (really want a new modem though...).

As of the router, I don't remember the specific model, but it is a 70$~ Cisco router.

Every machine goes dead. First, they become awfully slow, realllllly, unbearable slow, but then everything finally falls (Windows doesn't give me the "warning" icon when it finally dies though like it would do if the internet goes down for other reasons).

I too think it should work fine. We rewired everything with the help of a technician, but it's still the same.

Try assigning a static IP address to everything. Is the switch/hub just a simple switch/hub or can it assign IP address? If it can, make sure thats turned off.

quote Saga

Every machine goes dead. First, they become awfully slow, realllllly, unbearable slow, but then everything finally falls (Windows doesn't give me the "warning" icon when it finally dies though like it would do if the internet goes down for other reasons).

Are you talking about just the internet connection (as in the internet is really really slow, then no internet connection)? How long does each stage last until you can connect back again?

quote Saga

Can someone confirm that this is true? The technician I asked a while ago told me that I should be able to access either the modem or the router via their IP addresses, but NOT both. We have rewired things and I can still access each one of them with their respective IP addresses. If this is true, I think the problem may be there.

You should be able to access both the modem and wireless router from their IP address. I've done it before with my setups. You just have to make sure they both have different IP address.

It shouldn't be too hard... I do it on computers sometimes just for the hell of it. Change the internet settings on each computer in the adapter settings (for windows). You will have to set the IPaddress, default gateway (IP address of the router), and DNS servers (you can use googles DNS servers (8.8.8.8 and 8.8.4.4) or set it to the router).

That way, instead of the router assigning your computer an IP address, the computer already has one to use. You can still let other computers on the network which don't have assigned IP address, the router will just give it one automatically.

I have networks with a mix of static and manual IP addresses, and never had a problem.