The strikes apply to the board only, and are independant of the IRC, and last for 15 days. You were banned from the IRC for other reasons. However you were only banned from #undergroundnews and not the servers themselves. You should still be able to connect to the chat.
If you feel that you don't deserved to be banned, or would like to ask to be allowed back in then please PM one of the global mods or the admins.