What is happening is the mapped drive is sitting idle for 15 min and then disconnecting to free up resources. DB applications such as yours get these errors because this connection is not persistent as g.jacobse has eluded to with the /persistent:yes command. This will keep the drive mapped but does not stop the idle timeout from occuring which will continue your error.
Do this on the machines in question: (also can be deployed via Group policy script)
Open CMD then right click and run as administrator
net config server /autodisconnect:-1
This will set the autodisconnect to never disconnect and you should not see this error any more.
Give it a try and report back your findings.