TC + Cable modem = no IP over wireless?

[C8XY]

A friend of mine is having trouble with his TC, his broadband connection is through a cable modem and not a router.
We can set it up so the internet works fine when connected to TC via ethernet but the wireless fails to connect, it just times out.
We can access the TC wirelessly to change settings etc. so I'm sure the problem is something to do with sharing IP addresses.

I have a TC connected to a router and works fine, we compared settings and this didn't work, we've been through the manual, all to no avail.

Does anyone have any ideas how to sort this?

His broadband service is Virgin Media in England. (dynamic IP)
We have only used DHCP settings (not PPPoE (account + password req.?))

And yes it backs up wirelessly, so it must be an address problem right?

Please help! He's on the verge of returning it!!

 

[harry454]

open up more ip address ports, it seems he has more wireless devices trying to connect rather than the number of ip address open

 

[C8XY]

open up more ip address ports, it seems he has more wireless devices trying to connect rather than the number of ip address open

In the modem settings?
The modem only has one ethernet port but surely it will give out more than one IP address? He had an old netgear wireless router connected to it before that would give out a wireless signal to at least 3 devices.

Sorry I'm a bit of a noob with networking

 

[bubbamike]

The Cable modem is just a modem right? Set the Airport to act as a DHCP server for your Lan. It will assign IP addresses to the network. Make sure you have NAT and SPI enabled to protect your lan computers. The modem shouldn't be acting as a DHCP server for the Lan unless it is also a router.

 

[harry454]

yes all config should be done through the TC not the modem, plus you cant even config a modem

 

[C8XY]

The Cable modem is just a modem right? Set the Airport to act as a DHCP server for your Lan. It will assign IP addresses to the network. Make sure you have NAT and SPI enabled to protect your lan computers. The modem shouldn't be acting as a DHCP server for the Lan unless it is also a router.

Could you (or someone else) please write an "idiots guide" on how to do this!

Also the modem is definitely just a modem, not a router.

Thanks!

 

[harry454]

I can see if I get time later today to write a guide, but I bet you applecare could help you easily with, try giving them a call