On the affected machine, could you please try to ping www.ubuntu.com and archive.ubuntu.com? I can reproduce the lack of ping response from www.abc.net.au, but this may be related to the www.abc.ne.au network connection, rather than either my or your local connection.
On the affected machine, could you please try to ping www.ubuntu.com and archive.ubuntu.com? I can reproduce the lack of ping response from www.abc.net.au, but this may be related to the www.abc.ne.au network connection, rather than either my or your local connection.