Strangely I'm still getting the "Can't reach server" error. I don't have time to try much right now, but I'm not sure what I can try on my end - I've tried the different tekkit versions and reinstalling it, but this still happens. I don't know why I would be able to see other servers though, when it doesn't even seem to register that this server exists.
I haven't tried running a server myself, but is it possible something happened with the whitelist, maybe? Again, I doubt that would prevent me from seeing the server in the first place, I'm just not sure where the problem lies.