This Url leads the public thru an Ops Mgr tutorial,
https://docs.opsmanager.mongodb.com/current/tutorial/install-simple-test-deployment/?_ga=1.48123875.514616956.1461687856

The above instructions have you place the appdb and backup(db) in /data/(xxx) using dbpath.

The /etc/mongod.conf that is generated does not use same dbpath value. Thus, when you reboot, a new appdb is created missing your data.

The result is that you can not log in to the Web UI for Ops Mgr.

–

Workaround; manually edit /etc/mongod.conf

Repair; generate better settings in /etc/mongod.conf