Really weird network problem... Please help!

Question

This is really starting to tick me off, so I hope you can help me. This isn't exactly Archlinux related, but the problem persists on the whole network regardless of OS being used.
Ok, so I got my new D-Link 5-port switch home a few days ago. I wanted to hook up my laptop so it could access the internet.
I'll try to illustrate how the layout of the network is made up in my home:
Internet -------> Router -------> Switch -----------> My dad's computer
                                                         |
                                                         -----------> My switch -------------> My main desktop
                                                                                         |
                                                                                         -------------> My laptop
As you see, we split the internet between our 3 computers, where 2 of them are mine, and 1 is my dad's. The problem is, that we can't run more than 2 computers online. DHCP just won't function.
If I have both of my computers online, my dad can't connect to the internet. If my dad has his computer online, I can't connect with 1 of my computers. So we are constantly only able to be 2 on the internet. I see no logical explaination for why this is happening, because the internet is split on the first switch, to my dad and me, then from my own switch, I split my connection between my 2 computers.
Please help me, this is really giving me an edge. I REALLY hope you can help

Answer 1

SomeoneWithAPurpose wrote:IP-Address: 87.58.149.226
That confirms my suspicion.
I think I can explain the problem. Every computer that connects to a network needs an IP address. Normally you connect a router to the internet and the router gets a public IP address from the ISP's server. This is the address that people see when you connect to their sites. When you connect your computer to the router, the router gives you a different IP address. that only people on your LAN can see. The router can give several addresses because they are only used on the LAN, so you can connect multiple computers to it and each one can get a unique IP address. When you connect to the internet, your computers communicates with the router using private IP addresses on the LAN, then your router communicates with computers on the internet using public IP addresses.
In your case, your router is not configured to give out IP addresses. Instead, when you connect you are getting a public IP address directly from the ISP's server. Your ISP only has 2 public IP addresses that it can give you so that is why you cannot connect more than 2 computers at a time. You need to configure your router to act as a gateway between your LAN and the internet. To do this,  you have to access the router's menu and set up a dhcp server (which gives out IP addresses on the LAN) along with a firewall and whatever else you need (your current setup makes your computer directly accessible from the internet which can be unsafe, especially when running Windows).
Oh damn.
I went downstairs to find out where the manuals for the router were... Turns out we don't have a router ...
All we have is 3 boxes; A internet phone adapter, a ethernet xDSL modem and a switch. Maybe this is why it's all ****ed up? Sorry for the misleading, but my dad always told me that we had a router. =\
Ah... yeah, that's a problem. What brand is the modem? Maybe it has some router functionality anyway.
Last edited by Xyne (2009-04-26 00:43:04)