502 Bad Gateway when accessing OpenClaw UI on Brev

[kegetaneh]

Environment:

• OpenClaw version: 2026.3.11 (29dc654)
• Brev instance: openclaw0-q57d5sznt.brevlab.com
• OS: Ubuntu (ubuntu@brev-q57d5sznt)

Steps to reproduce:

1. SSH into Brev instance
2. Run: CHAT_UI_URL=https://OpenClaw0-q57d5sznt.brevlab.com bash /home/ubuntu/OpenShell-Community/sandboxes/openclaw-nvidia/openclaw-nvidia-start.sh
3. Gateway starts successfully (pids confirmed, ports 18788/18789 active)
4. Open the UI URL in browser

Expected behavior:
OpenClaw UI loads at the brevlab.com URL
Actual behavior:
502 Bad Gateway — Cloudflare reports Host Error. The public URL never becomes reachable.
Root cause from logs (/tmp/gateway.log):
A config change (gateway.auth.token) is detected immediately after startup, triggering a gateway restart. The restart fails because the original process is still holding port 18788, causing a lock timeout after 5000ms. The gateway ends up in a broken state.

Tried:

• Multiple restarts
• openclaw gateway stop then restarting
• Running inside tmux
• All attempts result in the same 502 error

Screenshots of the 502 error and gateway log attached.