TCP port for 2017 is 7203.
Changes in MSSQL 2017 AO
The MSSQL 2017 instance with AO setup on multiple, like 4 IP's. So if you do an nslookup you get back all 4 IP's. Then the client is supposed to connect to all 4 and ask each one, are you read/write or read/only. Then depending on the query type the client can use whatever connection it wants.
To connect to 2017 the driver / client MUST be AO aware.
AO setup for 2017. AO aware makes for much better fail-over. If the DB's ever move the clients detect the change instantly.
for sqlserver 2012 n 14 working because
The 2014 and 2012 instances are setup to support systems that are not AO aware, and we use DNS changes to update clients which can take 2 minutes, so when a fail-over occurs we can see a loss of connection to SQL for up to 2 minutes.