As the title suggests, I've spun up a docker instance on a Ubuntu 22.04.2 host using the latest official image from Docker Hub. After completing installation, everything seems to start up and function as expected. Except that I cannot register the server with Vembu Portal. Upon attaching to the docker instance, I can confirm it has internet connectivity and DNS resolution. The error in the interface is as follows, but leads to a KB about a Windows-based installation: 

Please advise if this is a known issue or if there's some solution I'm missing.