By default, the PolyBase data movement service connects to the head node of a scale-out group over a range of ports from TCP 16450-16460, typically using 16450-16453, plus port 17001. These ports are only used when a PolyBase scale-out group is configured and should be allowed through server firewalls. SQL Server Setup should automatically create a local firewall rule allowing these ports upon feature installation. For more information, see Configure PolyBase scale-out groups on Windows.
Note
The Microsoft SQL Server PolyBase scale-out groups will be retired. Scale-out group functionality will be removed from the product in SQL Server 2022 (16.x).