At home I used a Net Gear 10 port hub to connect two PCs to our DSL modem. Plug in, turn on, tune out. Now my daughter is away at college and she has a cable modem. She's running WinME on a Dell L1000 1 GHz Celeron. Her roomie is running a Mac. Model unknown. Only one of them can be on line at a time. If the one logs on, the other gets booted off. She is running Norton 2000 Anti-virus and Zone Alarm. Any suggestions as to why this is happening? Could it be caused by her roomie using a cable with a connector on it (two shorties joined together with a two-way RJ45)? Or is it just Time Warner pocking us over?
Coax cable line comes into appartment and connects to cable modem. Coax then goes out to TV. Cable modem sits in daughters room with Cat 5 patch cord running from modem to Netgear hub. Cat 5 goes from Port 1 to daughter's PC. From Port 2 goes another Cat 5 to roomie's room with RJ45 connector/splicer/joiner/double female hoozit joining two shorter cables. No router, only hub.
Unless the cable modem has NAT capabilities (unlikely), you are seriously confusing the cable modem.
The ISP probably only provides one IP per cable modem.
That IP address is given to the computer currently using the cable modem.
No two computers on the same network can have the same IP address, so when two try to access the same IP address, one gets kicked.
To fix the problem:
First, you either need a router or you need to use internet connection sharing on one computer.
Second, get rid of the splitter and run two longer cables connected to their own socket.
If you have any other questions, I'm sure someone here will be able to answer them.