Noticed this first in Y14 (and later Y18), but it works with the normal Y version aswell, so it better put this here

Try to join any private server with a wrong PW, go back to "List of Hosts" and refresh the host list you'll get a "no reply" from all servers. Going back to "Multiplayer" and than again to the server list will fix it again.

Have had same problem sometimes, was confused why doesn't servers come up...

Ye, i had that once as well, pretty weird...

Hi,
just dropped in to inform you that this issue has been mentioned couple pages back under "Master Server" Bug topic.
I explained there in more detail how this happens (it's not just wrong password).
I would just like to add that probably any kind of failed connection to a server causes "No reply".
Maybe you guys find it helpful knowing you're not alone
Later...

I would have never searched under "master server" problem...

sometimes useful thread names would help a lot