On the off chance that I’ll forget or someone else might wonder how to get these two great services to work together, here’s the scoop. If you have small children (or older children who are grounded but still need to do homework and collaborative writing projects), you might have the web filtering for Microsoft Family Safety tuned to “Allow list only”.
In that restrictive mode, you’ll need to add the following domains to the allow list for FSS in order for SharePoint Online to work correctly (or much at all):
This is a subset of Office 365 URLs and IP address ranges. Some of those can probably be edited out for just pure SharePoint Online functionality with Office 365, but I didn’t take the time to experiment further.