# upstream connection failed: The upstream host could be down

- Link: https://www.agilicus.com/faq/upstream-connection-failed-the-upstream-host-could-be-down/
- Published: 2024-07-19T17:55:09+00:00
- Author: Don Bowman

The end-user receives this message on sign-in:

    ```wp-block-code
    Message: upstream connection failed
    Action: The upstream host could be down
    ```

This indicates the Agilicus Connector is up, and the user was able to sign in correctly,
however, the customer-supplied application is either down, or unreachable from the
Agilicus Connector.

![Upstream Connection Failed: Troubleshooting guide showing potential causes, including
a down upstream host, with a diagram illustrating the network path and potential
failure points.](https://www.agilicus.com/www/7e287088-diag-1024x344.jpg)

A common issue is a change in IP/port of the application, you may change this as
below.

![Upstream Connection Failed: Troubleshooting network connectivity issues. Diagram
illustrates potential network problems causing upstream host to be down, affecting
service availability. Learn to diagnose and resolve upstream connection failures.](
https://www.agilicus.com/www/7d4863b1-network-1024x461.png)

To diagnose the issue, use the detailed stats from the connector overview page:

![Agilicus upstream connection failed: Diagram illustrating a failed connection 
between a client, Agilicus, and the upstream host, indicating a potential issue 
with the upstream host being down or unreachable.](https://www.agilicus.com/www/
fd868928-image-1024x456.png)