How can I set this up behind a reverse proxy?

Hello all. I’d like to run Bitwarden next to a Nextcloud all in one instance. I’ve already completed the setup of Nextcloud following their reverse proxy guide.

Now I’d like to run Bitwarden on another subdomain but I always receive the error:

docker: Error response from daemon: driver failed programming external connectivity on endpoint certbot (6c4f9c0432d2a5283e9946c2c85073338b99cb40d050d4f69dfe515ffa7c23ba): Bind for failed: port is already allocated.

I wonder how I can fix that. I’m not that technical and I don’t know where to start and what to do.

I used the install script.

If you’re not technical, why are you attempting to host your own Bitwarden server instead of leaving the hosting to the pros, who know the ins and outs of keeping server data secure from online attacks, and who have the staff and resources to ensure server downtime is avoided or minimized?