Installation error - Cannot start service web, address already in use

Hello,
Running Step 9 of installation, I got an error:

ERROR: for talkyard_web_1  Cannot start service web: driver failed programming external connectivity on endpoint talkyard_web_1 (5852cd9052079346c8185603c2d2451ad3d3352e1cb8fceeb691812a9448b561): Error starting userland proxy: listen tcp4 0.0.0.0:443: bind: address already in use

On

docker-compose ps

I got:

  Name                     Command                State                   Ports              

---

talkyard_app_1 /bin/sh -c rm -f /opt/talk ... Up 3333/tcp, 9000/tcp, 9443/tcp,
9999/tcp
talkyard_cache_1 docker-entrypoint.sh redis ... Up 6379/tcp
talkyard_rdb_1 /chown-logs-then-exec-entr ... Up 5432/tcp
talkyard_search_1 /docker-entrypoint.sh /bin ... Up 9200/tcp, 9300/tcp
talkyard_web_1 /bin/sh -c /etc/nginx/run- ... Exit 128

So I inquired what's using port 80 with

sudo lsof -i :80

and found Nginx using this port:

COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
nginx 19819 root 6u IPv4 46549 0t0 TCP *:http (LISTEN)
nginx 19819 root 7u IPv6 46550 0t0 TCP *:http (LISTEN)
nginx 25491 www-data 6u IPv4 46549 0t0 TCP *:http (LISTEN)
nginx 25491 www-data 7u IPv6 46550 0t0 TCP *:http (LISTEN)

So I stopped Nginx with

systemctl stop nginx

Then Step 9 was completed successfully, and all the containers were up:

  Name                     Command               State                                   Ports                                 

---

talkyard_app_1 /bin/sh -c rm -f /opt/talk ... Up 3333/tcp, 9000/tcp, 9443/tcp, 9999/tcp
talkyard_cache_1 docker-entrypoint.sh redis ... Up 6379/tcp
talkyard_rdb_1 /chown-logs-then-exec-entr ... Up 5432/tcp
talkyard_search_1 /docker-entrypoint.sh /bin ... Up 9200/tcp, 9300/tcp
talkyard_web_1 /bin/sh -c /etc/nginx/run- ... Up 0.0.0.0:443->443/tcp,:::443->443/tcp, 0.0.0.0:80->80/tcp,:::80->80/tcp

Yet I have not found anything at the "talkyard.vimuttimag.ga" page. When I opened the home page of my website, I got Talkyard "Create admin account" page instead of the Ghost I installed before, and on pressing a "Create Account" button an error message:

502 Bad Gateway [TyE502BGW]

Talkyard's Nginx server cannot connect to Talkyard's application server.
Is the application server not running, or is there some network error?

Please check if the 'app' Docker container is running: 'docker-compose ps'

The

docker-compose ps

showed that the "app" container is running:

  Name                     Command               State                                   Ports                                 

---

talkyard_app_1 /bin/sh -c rm -f /opt/talk ... Up 3333/tcp, 9000/tcp, 9443/tcp, 9999/tcp
talkyard_cache_1 docker-entrypoint.sh redis ... Up 6379/tcp
talkyard_rdb_1 /chown-logs-then-exec-entr ... Up 5432/tcp
talkyard_search_1 /docker-entrypoint.sh /bin ... Up 9200/tcp, 9300/tcp
talkyard_web_1 /bin/sh -c /etc/nginx/run- ... Up 0.0.0.0:443->443/tcp,:::443->443/tcp, 0.0.0.0:80->80/tcp,:::80->80/tcp

What should I do to properly integrate Talkyard to Ghost?