We have found that in the last couple days the security solution that our campus uses has blacklisted pythonanywhere. Our ITS staff can put in a temporary exception, but by IP only, and your hosting IP changes (they tell me). Specifically, they say: "The reputation filter comes from a distributed list from DVLabs, which is part of Trend Micro. This list is distributed directly to our Intrusion Prevention System and changes regularly. It gives us no other information other than it has a reputation score of 80 (the higher the score, the more risky the site). We normally block any site above a score of 60."
Sadly, this will mean no pythonanywhere for our class next fall, unless there is a way to get your "reputation" with DVLabs repaired.