I am using Ubuntu 12.04. I use DSL connection and I configured it using the most common approach, using the network manager in the upper panel. But recently I am facing problem. Though my internet connection is ok and I can connect it using Windows I can't connect it all the time using Ubuntu. Sometimes it works and sometime it isn't. If connection is dropped while using, sometimes I can't connect it again unless restarting the PC. So I thought of configuring it raw using terminal. How can I do it?
I think you might need to consider UFW, I mean the firewall of Ubuntu. See if the outgoing connection is enabled. Also it could be a problem of your ISP.