LimeWire does not support proxies in any form at this time, although we would like to in the future. You may be correct that this is a DNS issue in your case. I would recommend adding 64.61.25.139 (the ip address of router.limewire.com) to the "AutoConnect Hosts" section of the "Connection" tab. This will cause LimeWire to attempt this address directly on startup, as long as you have the "Prefer AutoConnect hosts..." option selected.

You could also try manually adding this address in the top Add, Remove text field in the Connections tab. Keep in mind that it often takes a little while to get a connection to router.limewire.com because there are so many people attempting to connect.

Hopefully this will help. You could also try manually attempting to connect to gnutellahosts.com, as that will give you valid pongs (gnutella pongs/addresses to connect to on the network).