--oplogSizeMB is the configuration file's key (replication.oplogSizeMB); mongod refuses it as a flag, so setup.sh's replica-set step left the unit restarting until the flag was fixed on Max. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw