The bug has been opened on https://bugs.launchpad.net/bugs/146434

"Binary package hint: xchat-gnome

Oz.org is wrongly called OzNet.

OzNet connects to sydney.oz.org and melbourne.oz.org which don't exist.

The correct servers are as below taken from www.oz.org

# germany.oz.org - Overseas clients can use this server.
# sandiego.oz.org - Overseas clients can use this server.
# us.oz.org - germany and sandiego.oz.org
# irc.oz.org - servers anyone can use - at this point it's the same as us.oz.org
# rockhampton.oz.org - only works from gov/edu clients
# wollongong.oz.org - only works from gov/edu clients
# waix.oz.org - AU only clients, works only if your ISP peers with waix (bigpond and optus currently don't)."