Difference between Client Access Name in SQL server Fail over Cluster and Always on availability group We are migrating from SQL Server Fail over Instance to Always On Availability group. The current network name is ABC\ABCTEST where ABC is the SQL server Virtual Name  and ABCTEST is the named instance name. In always on availability group all the connection will make connection through the Listener name for example Listerner123 and it will not use any instance name and the replicas are standalone. 

Now is there any way to have the name as VirtualName\InstanceName  or we will simply use the Listener name in the connection strings
There is a way: use alias on source machine. Anyway, if possible, I suggest you to correct connection strings.