Nextcloud, db connection failed :( false ip ?! false ports? ports blocked?

Hello, I have installed nextcloud with docker-compose. Nextcloud is running, but it can not connect to my maria db.

my mistake:
SQLSTATE [HY000] [1045] Denied access for user 'nextcloud'@'' (with password: YES)

but that is not my ip;). 2 years ago I had the same problem with Mailcow. I changed the ports and it works.

I have mapped my port 80 to 8888. (nextcloud_app)
nextcloud_proxy "/app/docker-entrypo…" 2 hours ago Up 2 hours>80/tcp,>443/tcp

However, the nextcloud_web port is 80.
nextcloud_web "nginx -g 'daemon of…" 2 hours ago Up 2 hours 80/tcp

I believe my mailcow: 80 (nginx) blocks my nextcloud_web: 80 (nginx)

Or is that okay? I used docker-compose.yml (with-nginx-proxy-self-signed-ssl/mariadb/fpm).

Is this my problem? How can I change this port? I tried docker-compose.yml with these lines

- 8888:80

but that failed

okay, I’ve overlooked the web/nginx.conf …