I've been having this problem since I reworked my network. Here's the setup:
Cable Modem > Linksys router > switch > various CAT5 cables to a patch block > lines out to around the house.

In order to use the program and get around the firewall issue, I need to forward a TCP port. I can see how to do this in the admin page for my router, but I have a problem. For some reason DHCP settings are very erratic. Sometimes there will be no computers in the DHCP clients table, other times they will all be there, other times the same computer will be there twice! I try refreshing the list several times, but nothing happens.

There are currently three computers on the network. Two desktops plugged into the switch, and the Tivo directly into the router (it wouldn't work any other way). None of these have DHCP assigned addresses, despite the fact that the Turbonet on the Tivo requires DHCP, and the Tivo is able to connect to the net.

Please help!

There should be a way on your router to specify static IP's for computers based on their MAC addresses. Then you can forward ports to the static IP that is assigned to the computer you want to forward ports to. At least that's how I think it should work, linksys may do strange things.

Matthew

I've noticed that the DHCP clients list on my friends' Linksys routers are always underpopulated, too.

The obvious answer would be to assign static IP addresses for those machines that need to have a port forwarded to them. But assigning specific DHCP addresses should work, too.

How do I find the MAC address for a specific machine? The router seriously makes it look like there are no machines on the network, and that's puzzling me

type:

ipconfig /all

at a command prompt. Physical address is your MAC address.

Or if it's a machine elsewhere on the network, ping it, then type arp -a in a command shell.

How would I ping it?

Get nmap.

C:\nmap-3.45>nmap -sP 10.10.10.0/24

Starting nmap 3.45 ( http://www.insecure.org/nmap ) at 2003-09-25 22:24 Pacific
Daylight Time
Host ricin (10.10.10.1) appears to be up.
Host chiana (10.10.10.16) appears to be up.
Host isabel (10.10.10.18) appears to be up.
Host 10.10.10.100 appears to be up.
Host tivo2 (10.10.10.151) appears to be up.
Host riocar (10.10.10.201) appears to be up.
Host guardian (10.10.10.254) appears to be up.
Host 10.10.10.255 seems to be a subnet broadcast address (returned 6 extra pings).
Nmap run completed -- 256 IP addresses (7 hosts up) scanned in 14.841 seconds

C:\nmap-3.45>arp -a

Interface: 10.10.10.12 --- 0x10004
Internet Address Physical Address Type
10.10.10.1 00-a0-cc-58-d5-9c dynamic
10.10.10.16 00-a0-cc-58-b5-95 dynamic
10.10.10.18 00-30-48-21-5a-b8 dynamic
10.10.10.100 00-04-5a-f6-17-3c dynamic
10.10.10.151 00-0b-ad-21-d9-03 dynamic
10.10.10.201 00-02-d7-26-0b-0e dynamic
10.10.10.254 00-50-da-65-cb-de dynamic

Hehe, I'll check it out. I'm having a problem, though:

My roommate unplugged his cable to give to another person (visiting) so he could log on to our network. When that person was done, he plugged the cable back in to his computer, and now it won't connect to the internet and he can't see other computers on the network. I also can't see his computer on the network. His link light on the switch is lit, and the router seems to be able to see him (there's an entry for him in the DHCP table now). I have no idea what is wrong. Help!