Comment 32 for bug 420999

I have had this problem as well with AT&T broadband and a Sierra Wireless USBConnect 881 on a fresh install of Karmic. I was previously using Jaunty and had no problems, and upgrading Jaunty to Karmic caused no problems. A fresh install of Karmic exhibited this behavior.

Everything seemed to work fine on the connection to AT&T broadband, I couldn't reach any websites. (Once or twice, the connection seemed to work fine, but there was no apparent commonality to any actions I had taken to get it to work.) Disconnecting, unplugging, rebooting, and restarting network manager seemed to have no effect.

After reading this bug, I checked my /etc/resolv.conf file and found that it had no entries in it. I added an entry for "nameserver" with the first ip address on the opendns site and everything began working fine, even after disconnect and reconnect.

By doing the following, I was able to add DNS entries to the connection so that it works consistently:

Right click on the network manager icon in the top panel, and select "Edit Connections..."
Choose the "Mobile Broadband" tab.
Select the "AT&T Data Connect" entry and click the "Edit" button. (an editing dialog appears)
Choose the "IPv4 Settings" tab
Change "Method" to "Automatic (PPP) addresses only"
Enter your nameserver ip addresses in DNS Servers, separated by a comma or semicolon. I entered the opendns entries as follows: 208.67.222.222, 208.67.220.220 but you should check their website and see if these are appropriate for you. If I can dig out the AT&T nameserver ip addresses, I may change to them, though opendns seems to work well so far.

I don't know what the overall problem is or if this helps resolve it (or if it has already been resolved!), but I hope this info will help anyone who has a similar problem.