I've found the solution.
What I'm trying to do is called Read-Only Routing List.
To configure you should assign a new URL to any server with the command:
ALTER AVAILABILITY GROUP [Availavility Group]
MODIFY REPLICA ON N'Replica Node' WITH (SECONDARY_ROLE(READ_ONLY_ROUTING_URL=N'tcp://route:1433'))
and then assign to the primary node a list of routing to secondaries:
ALTER AVAILABILITY GROUP [<your availabiliry group>]
MODIFY REPLICA ON N'<your availability group replica>' WITH (PRIMARY_ROLE(READ_ONLY_ROUTING_LIST = (N'<first preference replica>', N'<second preference replica>')))
All information found here: