I have a location that currently has an on-prem file servers. I'd like to get as much of that moved over to Sharepoint Online as possible. The big problem is they could be without Internet connectivity for a few days at a time during hurricane season. Is there a way to have those files cached locally so they could still collaborate if they don't have Internet access? I've looked into Azure File Share with Azure FileSync, but with port 445 being blocked by most ISPs it's kind of a pain for users working at home.