80 and 443 are the standard ports for webpages (http and https respectively). Lot of selfhosted software with web-based frontends will therefore try to use them.

You can change the ports for the bitwarden container to whatever you like, but the "proper" way to set up multiple services with web-based interfaces like this, is to use a reverse proxy to make them all accessible via these two standard ports. (Caddy is popular for this)

You can then access them using their respective subdomains or subpaths.

@GregorTacTac If you use containers you can map something like 8080 on the host to 80 in the container. Generally it's recommended to have a reverse proxy listening on 80 and 443 with all your individual applications on localhost only high ports.

With vaultwarden it's very easy, just change the port map in the docker compose file on the host side. No idea how to do it with the official server stack.

Unfortunately, I’m not familiar with installing Bitwarden so I can only offer general advice.

Port conflicts happen at runtime, not when software is installed. In general, you should be able to install as much software as you’d like that all relies on port 443 but only run one at a time.

If you’re seeing port conflicts when installing Bitwarden, then I suspect that something is starting the app after the install is done. If this is right, then maybe you can disable the automatic start. Or maybe you can ignore the error at install time, then configure the app, then start it.

https://bitwarden.com/help/install-on-premise-linux/#configure-your-domain

You'll want to use a reverse proxy with separate domains/subdomains for each service.