has not connected to internet automatically to the internet on start, which is configuration file of pppoeconf, to check it?

hello.
my installation of ubuntu op. system (8.10) has not connected to internet automatically to the internet after start of computer, which is configuration file of pppoeconf, to check it?
i connected to the internet with pppoeconf and set it to connect it automatically after turning on of computer. i think may be configuration changed after update.
why can be that it did not connect automatically.