If any of the apps don’t open with “502 Bad Gateway Error” or “site cannot be reached error” as shown in the below screenshots.
Try reinstalling the app with the existing config for a couple of times as depicted in the below picture.
If the issue still persists reinstall the app by removing the existing config and install the app with a new config.
After pressing the keep config / remove config button you will see ‘preparing’ status which is where the background process is being done for the apps reinstall. During this stage do not interrupt or make any changes as it may result in data loss. This stage may sometimes take a longer duration of time to complete, but be patient. Successful completion of this step will resolve almost all the app issues.
A successful app reinstallation would look like this.