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Can two computers share a dsl line?

Doesn't work for my macs



11:29 pm on Mar 6, 2005 (gmt 0)

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I just convinced my family to upgrade to DSL ($70/mo out here in the boonies) from dial-up, assuming we could connect all of our computers to a switch, switch to modem, modem to wall. We have three macs running OSx, but for some reason only one will use the DSL at a time.

In the network preferences I have it set up to automatically configure DHCP. When only one computer is on, it works fine... it uses for the ip address, with the router address at, and for the subnet mask. But when I try to use the second computer it uses 169.254.x.x for its ip address, and won't work. In the network status part of its DSL connection it says, "DSL is currently active. DSL has a self-assigned IP address and may not be able to connect to the Internet."

When I try to manually change the IP to the same as the working computer it says that address is already in use. Any help would be greatly appreciated.


2:21 am on Mar 7, 2005 (gmt 0)

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2:29 am on Mar 7, 2005 (gmt 0)

WebmasterWorld Administrator incredibill is a WebmasterWorld Top Contributor of All Time 10+ Year Member Top Contributors Of The Month

By switch I assume you mean HUB?

If you have a router, you aren't using it right.

DSL - > ROUTER -> COMPUTER 1 / 2 / 3 etc.

DSL assigns DHCP address of ROUTER, not the computers

ROUTER assigns DHCP addresses of COMPUTERS, and it's an internal only address, not the address of the DSL IP.

The router manages the magic of translating internal network requests from internal IPs to external network requests with external IPs. Trust me on this, we have 5 computers at home on a router using a single inbound IP # from our broadband provider.

BTW, how did you have more than one computer on your old DIAL-UP line? were you using a proxy server on one of the computers and your browsers and email all connected thru one PC? If so, you will need to disable the proxy server and all the connections to it from the other computers so they talk to the router.


4:47 am on Mar 7, 2005 (gmt 0)

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I'm using a Siemens SpeedStream switch. From what I read, every time some new information is received at a hub it transmits it to every computer. This slows things down a bit, and can cause data collisions. Switches separate the lines of communication between the ISP and each node.

Although I have rigged a shared dial-up connection before, that's not what we have been doing up to this point. We have one telephone line and three computers, one person got to use the connection at a time... good luck calling us ever.

My dsl modem has a single ethernet port, so I had to get a hub/switch to allow us all to connect at once. I figured the ip address would be assigned to the dsl modem or switch. I think the 192.168.x.x IP address is just a generic lan address (similar to localhost, but for a network).

What you said about the IP assignment makes sense, and was what I figured.. but for whatever reason it's just not working.


5:09 am on Mar 7, 2005 (gmt 0)

WebmasterWorld Administrator incredibill is a WebmasterWorld Top Contributor of All Time 10+ Year Member Top Contributors Of The Month

Trust me, get a crappy little firewall router, 15 minutes later it will all work.


1:37 pm on Mar 7, 2005 (gmt 0)

10+ Year Member

A hub will not do what you want, hubs are unmanaged, and and the dsl modem would have to assign a different ip for each computer connected to it. meaning you would have to pay 70 for each computer, I'm sure you don't want to do that. A switch will do the exact same thing, unless you get a switch with NAT, most switches do not use NAT. Basically what is happening is that you only get one ip, the first computer to be turned on gets that ip. the other ones get nothing. With a router, you will need to set the login name and password for your dsl in the router, instead of on your computer. Your router will be connected to the dsl and your computers will connect through the router.


1:27 am on Mar 21, 2005 (gmt 0)

10+ Year Member

"it uses for the ip address, with the router address at, and for the subnet mask."

Your subnet mask will only allow for one machine. - network address - Ethernet address of your DSL router - ONE machine - broadcast address
DHCP can only assign using a /30 subnet (

There are many "cable/DSL" routers available to allow you to use 1 IP address facing your DSL "modem" and up to a whole class C block on your inside network. The router should have NAT (Network Address Translation) turned on. I have 4 machines at home sharing 1 IP address on my cable modem.


1:50 am on Mar 21, 2005 (gmt 0)

WebmasterWorld Senior Member jdmorgan is a WebmasterWorld Top Contributor of All Time 10+ Year Member

Just to add a vote here, a hub or a switch won't work. You need a router. A router distingishes between "upstream" to the internet, and "downstream" to your local area network. Amd as supermanjnk says, routers do the Network Address Translation needed to make your multiple machines look like one to the ISP.

Netgear and LinkSys make affordable Firewall/Routers. See NetGear FVS318C or FR114P, and LinkSys BEFSX41.

These models are just the ones I've recently seen in the local stores, so they should be easy to find. I'm sure others will have their favorites, but I intend these as examples of units that will do what you need them to do, and also keep intruders out.



3:36 am on Mar 21, 2005 (gmt 0)

10+ Year Member

Thanks for all the help everybody.

I ended up with a Netgear router and it works like a charm.

I'm guessing the reason my switch worked before with a dial-up connection was because one of the computers was acting as a proxy.

I had been avoiding spending the money on a hardware firewall, so I'm glad I was forced to get a router with one built in.


11:37 am on Mar 24, 2005 (gmt 0)

10+ Year Member

I've heard somewhere, that there is some software for sharing dsl on several computers. search it on G.

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