Microsoft’s new Network Performance Tool is a proof of concept for Office 365 tenants to check network connections to Microsoft’s network and Office 365. The tool might help you understand more about your connection into Microsoft, but it won’t fix any last mile problems.
If you’re responsible for running the local network used by an Office 365 tenant to connect to Microsoft’s network, you need to know about the IP addresses and ranges used for Office 365 endpoints.
People sometimes complain about Office 365 network performance. The root cause is unlikely to be in Microsoft’s network. It is much more likely to be in the “last mile” to the user device.