Ingress result missing images and css files

Hello together

i have a Rancher and RKE1 cluster with the default Rancher Nginx Ingress Controller configuration.
Even I have deployed the Ranger Hello-World Container.

If I configure an Ingress with the Rancher UI and enter the new Ingress URL than I can access the Hello World Application. But the Hello World Application dont show the images. In the Nginx Ingress Logs i can found the 404 ERRORs.

If I make a Port Forward to the Hello World Applikation. Than everything loks like expected.

The Cluster is in a private network behind a VPN.
The RKE Nodes can access the Internet only via a Squid Proxy.
We use CentOS 7.9. on all RKE Nodes.
The Firewall on the RKE Nodes are disabled.

At the moment I don’t have any idea to solve this issue.