Last year. I am in different Public School networks and SyncThing still got caught. I worked for hours to figure it out and just couldn't :( Did they beef it up since last year?
There are public relays which you can use (automatically unless you disable the feature), so NATing and firewalls shouldn't be an issue.
I think they're upset that the Network Administrator is blocking the system intentionally, not that it didn't make it through in the first place.
Don't upset your Network Administrators!
Well I am in about 10 different school districts and they all have different policies. I just won't do anything that won't work as a default so I can claim ignorance.