I'm one of the many who have RDS as ISP. I noticed that I could not connect to undernet's irc network for the last few days. Here's the result of a a short analysis : RDS seems to redirect all undernet irc dns queries towards bucharest.ro.eu.undernet.org which is their local undernet server. The problem however is that the server seems to stop working every now and then and hence one cannot connect to undernet.

There are two ways of fixing that :

1. connect to a irc server ip instead of a server name ( provided you have that info stashed somewhere )
2. use a different dns, such as openvpn. In order to do that, set your dns servers as 208.67.222.222 (resolver1.opendns.com) and 208.67.220.220 (resolver2.opendns.com)