Hi @LesD your question is clear, but many details of your setup are still unknown.
80 and 443 are known web traffic ports, but other ports are not. Which web server are you using? Can you provide your “routing” configuration?
It sounds like you desire a reverse proxy arrangement…which means that the traffic from passbolt would come back out through your https://mydomain.com:33443 server. This is typically the case when no public access is granted to the “backend” passbolt server.
If passbolt is on a separate server (or VM) behind a reverse proxy, it will need to also have it’s web server configured to function as such.
Provide more info - I’m confident someone here can help you.