Q: compressor failed: 4x error

I am having an intermittent problem with Compressor.   I am getting the error:

Failed: 4x Host ...

Failed: 3x Host ...

My current setup is a Macpro with 2 instances and another 2x iMacs clustered together. 

Normally this happened infrequently that running Compressor repair would clear the problem.   Now it seems to be happen far more often. 

Please assist