That was an IP for one of the old EU NCSoft servers, which was closed years ago. GW2 has been at Amazon since around PoF. The login servers are auth1.101.arenanetworks.com for NA and auth2.101.arenanetworks.com for EU, but note that they won't respond to pings. Interesting, so why does "gw2.exe -diag" then still try to connect to those? hmm...