Oh noes, the traversal server is dead
When you constantly get this message then something is wrong with the traversal server that distributes the hex codes. You can still connect to others, but now we'll have to use the Direct IP Connection provided by dolphin.
For hosting a direct IP room, continue onward. For people connecting to a host you do not need to do the following changes. Just enter the IP:PORT the host will give you in the same connect to netplay dialog as you would a hex code.