# How to resolve IP blocking issues 

**Author:** Pauline Narvas

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If you can't access Vercel-hosted sites and debugging tools show your IP address is blocked, the cause is most likely your ISP or network policy, not Vercel.

You might experience:

- **Inability to load Vercel-hosted sites**: Pages time out or return connection errors
  
- **Blocked IP addresses**: Debugging tools show your IP is being rejected
  
- **Multiple users affected**: Others on the same network experience the same issue
  

## Common causes

- **ISP throttling**: Some ISPs block or throttle access to certain websites during peak usage hours
  
- **Network policies**: Universities, offices, and other shared networks often have firewall rules that inadvertently block certain sites
  

## Resolve the issue on a shared network

If you're on a university, office, or other managed network, contact your network administrator or IT department. Provide them with any debugging information, including the blocked IP address and the domains you're trying to reach: `vercel.com` or `vercel.app`.

## Resolve the issue on a personal network

Contact your ISP's customer support and ask them to unblock the following:

- `vercel.com`
  
- `vercel.app`
  
- `76.76.21.21`
  

## General troubleshooting steps

If the issue persists, try the following:

1\. **Use a VPN**: A VPN assigns you a different IP address, which can bypass the block. Follow your VPN provider's setup guide to get started

2\. **Disable antivirus software or browser extensions**: Temporarily deactivate these to rule them out as the cause

3\. **Check your router's block list**:

- Log into your router's web interface (often `192.168.1.1`)
  
- Navigate to the security or firewall settings
  
- Remove any entries related to Vercel
  

4\. **Flush your DNS cache**:

- **macOS**: Run `sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder` in Terminal
  
- **Windows**: Run `ipconfig /flushdns` in Command Prompt
  
- **Linux**: Run `sudo systemd-resolve --flush-caches` in your terminal
  

5\. **Reset network settings**: Restore your network configuration to defaults through your operating system's network settings

## Get additional help

If you've completed the steps above and the issue continues, please contact [Support](https://vercel.com/help). Have the output of the Vercel debug script (`vercel-debug.txt`) ready to share.

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