This is my first time doing this so help would be much appreciated.. I have 3 hyper v servers one for active directory one for iis and one for sql. I have built a new machine that is offsite that I would like to replicate these servers there.
How do I do this do I first need to set up a site to site vpn for a constant connection for hyper v replication?
Then just set up hyper v replication and call it a day?
As @Alex H said before, you can set Hyper-V replica over VPN.
As an alernative, if you have for example 2 nodes that can handle all your production in one virtualized state, you can build a shared cluster and place VMs with your services in it. Thus you will consolidate your hardware, will be able to control your environment easily and your production will be highly available.
For this kind of scenarios you should look for something like StarWind VSAN, Unity VSA or HPE VSA. They offer free versions as well.
As you said you will need:
Have a look here https://technet.microsoft.com/en-us/library/jj134172(v=ws.11).aspx and be certain to test the failover (make some backups before) and if possible get some minimal monitoring in place (via powershell to send you an email with the replication status each day).
On top of that make sure that you follow the best practices for SQL Server on top of Hyper-V replica sets https://www.simple-talk.com/sql/database-administration/hosting-sql-server-in-hyper-v-replica-environment/
