1. Log in to any node in the ceph cluster.
2. Use "ceph -s" command to find which monitor is out of quorum.
3. Remove that monitor. $hostname is the hostname of the monitor not in the quorum.
ceph orch daemon rm mon.$hostname --force
4. Check if the monitor is back to quorum. If it is not back, do the following steps.
5. dd the monitor container service.
ceph orch daemon add mon $hostname
5. Add monitor back to quorum. $ip is the public IP address of the host.
ceph mon add $hostname $ip
6. Check if the monitor is working and back to quorum.