See the below TecDocs for more insight into specific problems in this area
Ensure, that the date/time (locale) on the DM and SS are in sync (keep different timezones in mind)
Increasing the jobcheck retry timeout may help
The configuration policy to look at are under "DSM->Software Delivery->Agent"
Communication: Maximum number of retries (Windows)
Communication: Maximum number of seconds to retry
Changing the connection from UDP to TCP for this server: TEC471865
Bulk mode problem: TEC1414784