A client recently asked me why RB2011 sometimes lose their config after the initial setup
They apparently lock up and there's nothing left to do but reboot electrically and start over
It's not normal and it's not something that should happen over multiple RB's. I guess normal applies, ensure latest ROS and FW. They may be applying config with safe mode on, losing connection and the board reverting changes.
I had the case with a customer, same symptoms. After some searches it appeared that the customer had made a configuration template, and then duplicated the config using "backup" and "restore" ! Which is not good for different devices, I told him to use export/import with .rsc files instead and his problems disappeared.