Hey Roger,
Just to add, the following guide contains most of the information on how to create stretched cluster.
https://learn.microsoft.com/en-us/windows-server/storage/storage-replica/stretch-cluster-replication-using-shared-storage
In addition, do not forget that synchronous replication and asynchronous replication have different networks requirements. For Synchronous replication, 1 GbE network connection with RTT less than 5ms is required.
Alternatively, you can build stretch cluster using the following guide:
https://www.starwindsoftware.com/resource-library/starwind-virtual-san-2-node-stretched-hyper-v-cluster-on-windows-server-2016/
Cheers,
Alex Bykovskyi
StarWind Software
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