Help diagnose this OpenClaw Android gateway connection failure.

Please:
- pick one route only: same machine, same LAN, Tailscale, or public URL
- classify this as pairing/auth, TLS trust, wrong advertised route, wrong address/port, or gateway down
- quote the exact app status/error below
- tell me whether `openclaw devices list` should show a pending pairing request
- if more signal is needed, ask for `openclaw qr --json`, `openclaw devices list`, and `openclaw nodes status`
- give the next exact command or tap

Debug info:
- screen: onboarding final check
- app version: 2026.3.20-dev
- device: Google Pixel 6a
- android: 16 (SDK 36)
- gateway address: http://100.87.116.90:18789
- status/error: Gateway error: unauthorized: bootstrap token invalid or expired (scan a fresh setup code)