Gateway Time-out for API call /api/v1/method.callAnon/registerUser

Description

I have set up Rocket.Chat with docker-compose following the docs. I have put an nginx reverse proxy in front of Rocket.Chat and am using LetsEncrypt to generate my certificate.

After the Docker containers start up I can access https://rocket.pgoetz.de/setup-wizard/1 and enter the admin information. When I submit the form it seems to call the API method /api/v1/method.callAnon/registerUser which times out after a while and I receive a 504 Gateway Time-out from nginx.

Server Setup Information

  • Version of Rocket.Chat Server: I tried 3.4.3 and 3.5.2
  • Operating System: Host OS running Docker is Ubuntu 18.04
  • Deployment Method: Docker
  • Number of Running Instances: 1
  • DB Replicaset Oplog: Enabled
  • NodeJS Version: 12.16.1 (in RC 3.4.3, I don’t know if it was different in 3.5.2)
  • MongoDB Version: 4.0.19
  • Proxy: nginx
  • Firewalls involved: none

Any additional Information

I don’t understand two things:

  1. I can’t find the API method in the API documentation
  2. Immediately before the failing method call a call to /api/v1/method.callAnon/getSetupWizardParameter (also not to be found in the docs) runs successfully and returns HTTP Status 200

What am I missing and what do I need to change to run Rocket.Chat?