To resolve the "server response is in an unrecognized format" with status code 504 in the Life Fitness Connect App, follow these steps:

1. Understand the Error: A 504 Gateway Timeout error occurs when the server acting as a gateway or proxy does not receive a timely response from the upstream server. This can lead to delays or failures in responses which the Life Fitness app interacts with - learn more.

2. Check Your Internet Connection: Ensure that your device is connected to a stable internet connection. A disrupted internet connection can lead to timeout errors and unrecognized formats. If you are using Wi-Fi, try switching to mobile data or vice versa to see if the issue persists - learn more.

3. Restart the App: Close the Life Fitness Connect App completely and then reopen it. Sometimes, restarting the application can help it to establish a proper connection.

4. Reboot Your Device: Power off your device and then turn it back on. This can clear temporary glitches that may cause the app to malfunction.

5. Update the App: Ensure that you are using the latest version of the Life Fitness Connect App. Updates often include bug fixes and improvements that can resolve connectivity issues. Check the app store for any available updates.

6. Check for Proxy Issues: If you are using a proxy server, ensure it is configured correctly. The gateway or proxy may be down or slow, which can cause a 504 error. If possible, try accessing the app without using a proxy server - learn more.

7. Contact Support: If you continue to experience this issue after trying the above steps, reach out to the Life Fitness customer support team for assistance. They can provide specific guidance or address any ongoing issues on their end - learn more.

8. Consider External Factors: Sometimes, the error may stem from server-side problems that are beyond your control. Check online forums or social media channels for any reports of widespread issues with the Life Fitness servers or the Connect App.

By following these steps, you should be able to address the 504 error message in the Life Fitness Connect App effectively.