Issue with Azure API Management Service and Container Apps Environment in VNET

Question

I have a setup where my Azure API Management service is supposed to communicate with backend pools that consist of three container apps, all hosted within an Azure Container Apps environment. This entire setup is housed within a single virtual network (VNet). While the API Management service can resolve the private DNS within the VNET and find the IP address of the Container Apps environment, it consistently returns a 404 error when attempting to send messages to the backend.

Here are the specifics of the issue:

• The API Management service connects to the backend pools in the Azure Container Apps environment.
• DNS resolution is successful, and the IP address of the Azure Container Apps environment is correctly identified.
• Despite this, the container apps do not seem to receive any traffic; no logs are generated for incoming traffic on any port.
• I have tested multiple ports, including 443, 31443, 8080, 8081, and 80, but none have succeeded. Both HTTP and HTTPS requests fail with a 404 error, indicating that the container apps are unavailable.
• I have deployed a VM within the same VNet and verified that it can resolve the DNS and ping the Azure Container Apps environment successfully.
• Using Wireshark, I confirmed that packets are reaching the environment and receiving responses, but the container apps themselves are not being reached.

I've exhausted my troubleshooting options and am unsure how to proceed. Below are some images illustrating the network setup, DNS resolution tests, and Wireshark packet captures for further clarity.

Any insights or suggestions on how to resolve this issue would be greatly appreciated.

Thank you in advance for your help!