Forums Connection Issues Unable to connect to certain servers

Hi, I'm kind of new to the IRC scene and I have been having this problem for some time now. I will go onto mIRC and want to connect to a server, that I have connected to before, but it will not be able to connect to it. I will try a different server that I have connected to before and it will work. Could this be because sometimes servers shut themselves down every once in a while? Or could be because of a problem on my side? Please help.

Servers can shut down or have other problems that take them offline for a time. They could also be full. That's why it's usually easier to use a random server (irc.undernet.org instead of a specific undernet server).