As a conclusion to this:
After switiching to FE2 and solving the issue with my Reverse Proxy to support web socket (Viewer Comments - #3 by AlexHofbeck)
all the past issues with our deployment went away. It would still be beneficial for us to think about a better deployment configuration based on Kubernetes (in discussions internally) but for now, the Docker Compose deployment works fine.
Thanks for your support @iainsproat