I scaled back to 1 instance for all applications and that resolved the issue.
Now I scaled back to 3 instances and it’s happening again.
The only application that I can run with 3 or more instances seem to be the nginx proxy. But as soon as I scale any of the application instances past 1 I get timeout issues.
Not sure why restarting the applications would not reset the connections but I don’t know enough about how internal networking works at fly to tell what’s going on. I don’t understand either why this first started to happen when I was deploying an unrelated app.
Please help to troubleshoot. I will run my applications with a single instance for now as it seems to remedy the problem but that’s obviously no long term solution. Especially as with a single instance I was seeing timeout and connection issues whenever I was doing a new deployment. For reference that’s what @kurt recommended here: Internal network DNS propagation and new deployments - #3 by jascha