To setup TFS environment in Azure Virtual Network it is required to join the SQL, TFS, RM etc VM to the domain in Azure VM (Using AAD is another option). Before adding the VM to domain controller static internal IP should be assigned.
For example the VM created below is for setting up SQL server.
Selecting pre-created cloud service is not mandatory here. Setting the virtual network as shown below is required.
Set static internal IP.
To add to the domain go to server manager, local server. Click on Workgroup.
Provide domain name.
Provide domain administrator credentials to add to domain.
Restart the VM.