One or more of the server network addresses lacks a fully qualified domain name (FQDN). To start mirroring without using ...

One or more of the server network addresses lacks a fully qualified domain name (FQDN). To start mirroring without using a FQDN, click "Yes." To specify the FQDN, click "No." Then, specify every TCP address by using the syntax for a fully qualified TCP address, and click Start Mirroring again.

This syntax is:
TCP://.[.]: