I host Caddy and Vaultwarden using Docker. The traffic into the reverse proxy, Caddy, works over port 443, not 1808 or 1443. Using the Caddyfile, you can tell Caddy which port to send the traffic over.

Caddy docker-compose.yml

services:
  caddy:
    ports:
      - "80:80"
      - "443:443"

Caddyfile, although there are other ways to do this

*.example.com {
        @vaultwarden host vaultwarden.example.com
        handle @vaultwarden {
                reverse_proxy :11808
        }

Vaultwarden docker-compose.yml

services:
  vaultwarden:
    ports:
      - 11808:80