OK, so first of all let's go over some basic stuff. I assume you're running Trains Server on some remote machine (i.e. not localhost), I also assume you can SSH to that machine... I also assume you're using docker-compose to run the server. In the server's console, can you try to:
Run sudo docker ps and see if the trains-fileserver docker container is up (and not restarting every few seconds) - its uptime should be roughly the same as that of the trains-apiserver or any of the other containers. Run curl http://localhost:8081 from the server's machine and see whether you get an error and not a timeout Open bash inside the trains-fileserver docker container using sudo docker exec -it trains-fileserver /bin/bash and try running curl http://localhost:8081 there, and see whether you get an error and not a timeout