I get that sometimes too, however one night I got it every 15mins or so, but it is just that I'm up here and server is down there, it is normally 300ms ping and not too stable, reads failed quite often, I actually took video from ping at login screen once, is somewhere and I can put up if that has any interest to see.
1M ADSL connection from largest ISP here is so can't do anything to get it better. Luckily it is more stable at normal times, just from about now to next 3 hours it is going to be bit bad so I try to avoid this time and log in at different time.