I installed AlwaysOn on my laptop (testlab) with three VMs, of which one is a domain controller and two are hosting SQL Server instances (planned to be one primary and one secondary replica). Everything went well until I wanted to add the secondary replica to the Availability group.
Please find a screenshot attached. I have already changed the port to 1433 in the TCP/IP settings and have also added an exception for SQL Server in the Windows Firewall. Both of the servers are in the same cluster network. Not sure what else I am missing here.