Can I use MSSQL's Failover Partner parameter without configuring database mirroring?

I have 2 MSSQL databases that are **not** part of the same cluster but they are synchronized manually (without database mirroring configured) I want my client applications to try connecting to the first DB host. if it fails, it should connect to the second DB host. I created a connection string (in Java) that looks like this : String connectionString = "jdbc:sqlserver://:1433;" + "database=;" + "user=;" + "password=;" + "encrypt=true;" + "trustServerCertificate=true;" + "failoverPartner=:1433;"; It connects correctly to the primary DB instance. but if I shut it down and the connection is redirected to the second DB instance the connection is blocked. (connecting this instance as primary works) Does the redirected connection rely on mirroring?