PC to ATT modem connects fine but not the TC

You need to put the TC in bridge mode. The existing modem you have is already a router.

Plug your computer into the TC.. select Internet in v5 utility or Network in v6 and choose off, bridge mode.. here it is in v5 which you can download and install on Lion.

You can then also setup wireless in the TC however you like.. I am not sure if the existing modem also has wireless.

It is a router. You can tell that from the IP address you posted.

The alternative method is to use PPPoE client on the TC as you previously had it.. but at some point the modem has gone back to router mode.. all modems are routers nowadays. It is all built into the one chip. But it can be deliberately turned off if you want.

It sounds like the supplied modem is a special job.. if it is that small and without a model number, I have no idea how you are supposed to get info on bridging. ADSL modems are cheap as chips now for a single port model.. we are using heaps of TP-Link now for bridge role.. 8817 or 8840T.. they are less than $25 for the cheapest one. They at least then have a manual and you can see how easy it is to bridge.

Hey, i have almost the same problem, i think. I live in germany and i have a Arris Touchstone TM602S modem. The modem was connected to the TC and everything worked fine until today. My modem is connectet to the internet, but my TC can't get the connection or only for some seconds. What i did then: i put the old router (D-Link wireless) between the modem and the TC, then set the TC to bridge mode. It's working again, but how can i get my old configuration back without using the D-link router? I hope my english is okay, maybe somebody knows a solution for my problem.

How was the TC previously configured.. if it was running pppoe client then something changed.. If you set the TM602S as router then the TC should be bridged.

It is worth just resetting everything and starting over.. but i am not sure of the authentication methods you use for your adsl.. you will need to tell us that.

Thanks for your help! I already solved it somehow: the TC is now again set as DHCP and NAT. In the internet configuration i set connecting with: DHCP, as well as IvP6 to atomatic configuration and IvP6-Modus to nativ. After that i restarted everything.

I'm not sure what i did with that, but it's working for now.

The TC was set pretty similar before, exept the IvP6 stuff. I don't need any authentication for connection with my adsl. That was pre-set by a technician from my provider. So everybody could plug in a notebook directly to the modem and it works.

I'm wondering where the trouble with the TC came from, because now it's just fine again.

With Mountain Lion it just needs the occasional reboot as the OS.. loses its marbles about what IP the TC has .. once a day is usually enough.. more than that talk to us.

If you have no authentication then you use IPoA.. or EthoA.. it is not so common method. But it makes your adsl more like a cable system.

There are many versions and it is better to do a google search specifically for your model number and bridge.

I cannot tell you how to do it.. We don't have that model in Australia.. you would do better ringing ATT support if they supplied the modem and getting them to talk you through the bridge option.

What I would do in your situation is go and buy another adsl modem.. we use heaps of the cheap TP-Link here.. 8817 or 8840.. cheapest are about $25. They have manual and are a snap to bridge. Any bridge modem will work just like any other bridge modem as you have a fixed speed line.