We expect Central to run on ports 80/443 and don't yet support other ports. We know folks want to run on other ports and have filed an issue to explore the possibility.
ODK Central with nonstandard port number and custom SSL: Cannot retrieve forms with Collect is a related topic that you might want to read for more information.
As to the custom DB server not working, run docker-compose logs --tail 50 and see what your logs say.