We have an AlwaysOn HA sql cluster set up, with read-only replicas in place, and read-only routing in place. We know how to properly route a connection to the read only replica (by specifying ApplicationIntent=ReadOnly connection property).
The problem: we have a "dumb client" from a vendor that queries our database hard for reporting purposes. We'd love to direct its connections to the read only secondary sql server and take load of our primary. But, the connection string properties can not be configured. We can only specify IP/Port/Creds. The vendor said it's not possible to specify connection string properties.
So is there any other way to force connections to query the read-only secondary server? I'm open to creative solutions like a proxy, automatic fail-back, etc.