# Network troubleshooting (RunCell remote unreachable)

> Fix remote connectivity issues (remote ping failed) in restricted networks, proxies, VPNs, or offline environments

Canonical HTML: https://www.runcell.dev/docs/faq/network-troubleshooting

## 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):

```bash
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):

```bash
jupyter lab --log-level=DEBUG
```

and contact support.