# Identifying a firewall or proxy server problem

Source: https://developer.avalara.com/avatax-for-ap/vig9105064706007/

# Identifying a firewall or proxy server problem

Learn how to identify and troubleshoot connection issues caused by a firewall or proxyserver.

If your software is unable to contact AvaTax, most API calls you make will produce anerror. So, let’s begin by explaining how we can identify whether a connectionproblem exists.

-   Sandbox Environment: [https://sandbox-rest.avatax.com](https://sandbox-rest.avatax.com/)

-   Production Environment: [https://rest.avatax.com](https://rest.avatax.com/)

If your connection is working correctly, you’ll see a page similar to thefollowing:

![A screenshot showing the rest.avatax.com site with links to AvaTax resources.](https://avalara-devdocs-prod.mcoutput.com/avatax-for-erps/Content/Resources/Images/DevDot/rest-avatax-com_876x359.png)

If you can’t see this page on your desktop computer at work, but you can see thispage from a mobile phone on the public internet, you likely have a networking issue.There’s a chance that your office has a firewall or proxy server that enforces somelimits on your network connectivity. Contact your corporate IT department for moreinformation.