The _check_control_plane_health() method probes localhost:18180, which
is the control-plane's mapped port. Inside a bridged container, localhost
resolves to the container's own loopback — the probe always fails.
host network mode shares the VPS host's network namespace so that
localhost:18180 correctly reaches the control-plane.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>