Network troubleshooting (RunCell remote unreachable)

When you need this

If RunCell works locally but can’t reach the server, your environment may be:

• Offline / unstable network
• Behind a corporate proxy / VPN
• Blocking outbound connections (firewall / allowlist)

Step 1 — Confirm basic connectivity

• Verify your internet connection.
• If you are on VPN, try toggling it off/on.
• Try a different network (hotspot) if possible.

Step 2 — Check proxy / firewall rules

In corporate environments, outbound HTTPS may require allowlisting.

• Ensure outbound HTTPS (TCP 443) is allowed.
• If you use a proxy, ensure your environment is configured correctly (common variables):

export HTTPS_PROXY="http://your-proxy:port"
export HTTP_PROXY="http://your-proxy:port"
export NO_PROXY="localhost,127.0.0.1"

Restart JupyterLab after changing environment variables.

Step 3 — Domain allowlist (if your org blocks traffic)

Ask your IT/security team to allow outbound HTTPS to:

• www.runcell.dev
• *.runcell.dev

Note: The exact domains used may evolve. If you need a strict allowlist, contact support and share your environment details.

Step 4 — Try again

After updating VPN/proxy/firewall settings:

1. Restart JupyterLab fully (stop the process, start again).
2. Reopen the RunCell sidebar panel.

Still not working?

Collect and share:

• Your OS and installation method (pip/conda/brew/docker)
• Whether you’re behind VPN/proxy
• JupyterLab logs (start with debug):

jupyter lab --log-level=DEBUG

and contact support.