Connection Error

For the past several days, if I package my app and try to scan it to my phone or download it to my computer I get

This site can’t be reached

The webpage at https://ai2.appinventor.mit.edu/b/nyu6 might be temporarily down or it may have moved permanently to a new web address.

ERR_INVALID_RESPONSE

Not seeing this issue here (UK - personal computer, at home), you may have a local network issue? What is your network environment?