This should work out of the box. If that's not happening then this should be escalated to the support hotline.
We have 3 workflows in place and during the job process Workflow manager will show the jobs fail with a error of "Failed to Print Failed to connect to server". This error is pretty random it can happen at any time with any file. Currently we have Free Flow going directly to the intergated Fiery on a XC560. During the time of failure we can ping the printer, within free flow printer registration we can send a test job and it goes through. Free flow is connected to the printer via IP so we are bypassing any issues with DNS.
On the printer itself we have the fiery upgraded to the latest service pack.
The version of Free Flow we are on is 9.011.0[9.0.11.01205.42]