Storage server is offline
storage-server-policy returned 503 Storage server is offline.
Why this happens
Admin set the server offline, or health marked it down. Distinct from Storage node is not connected yet (never connected) and Storage server is not available (broader).
Diagnose and fix
1. Admin → Servers — set the server online (Disk caps and offline servers).
2. Fix connectivity on remote nodes; retry.
3. Route uploads to another online server if this one must stay down.
4. See Storage server is not available.