no route to host when trying to connect to same sever from inside ssl-proxy

[worksasintended]

Hi there,
I am having the following issue: The proxy works fine to me. I use it to connect to a locally running nextcloud docker, but when I try to connect to the very same server (lets call him myurl.com) i can ping but not connect on https or https.
The parameters with which is start the container:
ssl-proxy:
image: justsml/ssl-proxy:latest
environment:
- HTTPS_PORT=8080
- SERVER_NAME=myurl.com
- UPSTREAM_TARGET=app:80
- CERT_PUBLIC_PATH=/certs/fullchain.pem
- CERT_PRIVATE_PATH=/certs/privkey.pem
- SSLProxyVerify=none
- SSLProxyCheckPeerCN=off
- SSLProxyCheckPeerName=off
- SSLProxyCheckPeerExpire=off
volumes:
- /home/nextcloud/certs:/certs:ro
links:
- app
ports: ['8080:8080']

If I now try to for example curl myurl.com I get no route to host, although there are running services on 80 and many other ports I can connect to from everywhere else. Any suggestions how to fix that would be appreciated. Thank you!

[worksasintended]

Correctly it does say host unreachable while the nextcloud ontainer gives no route to host.