Docker "No internet connection" even if remote admin, SMTP works

Hi, I have a fresh Docker compose installation and I am a newbie.

I can access the admin configuration remotely via http. I can send a test mail via smtp.google.com. But I get this via the same www interface:

## Security & setup warnings * This server has no working Internet connection.

curl -I https://marketplace.owncloud.com on the server works. docker-compose exec owncloud occ market:upgrade market hangs seemingly forever. ./occ market:upgrade market says PHP module ... not installed several times, then Exception: Environment not properly prepared.

I have .env file in the owncloud directory:

OWNCLOUD_VERSION=10.10
OWNCLOUD_DOMAIN=localhost:9090
ADMIN_USERNAME=admin
ADMIN_PASSWORD=admin
HTTP_PORT=9090

I also set these and environment variables in .bashrc. I created a Marketplace account, but I do not know where to put the API key.

How can I fix this?

The log (via www), since server restart, contains only this at a level >= 1:

{"reqId":"AJymyt5Ns8sSbxzC8DpM","level":1,"time":"2022-05-20T10:12:02+00:00","remoteAddr":"","user":"--","app":"cron","method":"--","url":"--","message":"Invalidating tokens older than 2022-05-20T09:52:02+00:00"}

Then there is another log printed via docker-compose logs --follow owncloud which shows a lot of www GET access data, but does not seem to report any errors.