Is that not a client connection flag? MARS does not require a setting change on the server?

I think you may have misinterpreted what he said. I can see why it seems to imply a server setting but that isn't the case

> Did you know there is a setting in MS SQL Server that impacts performance by an order of magnitude when sending/receiving data from the Cloud to your on-premises servers? It's the default in the ORM generated settings

You are right. For some reason when I initially sped through the post I read it as if RDS was doing something wrong.

It is a setting in connection string in the client app.config, "MultipleActiveResultSets=true;".

"Multiple Active Result Sets=true;"