My thought is that in this case the Local site can’t see jpanel.local within the virtual environment due to the VM/container not using your main /etc/hosts file.
Also, 127.0.0.1 in the site container won’t reference your WAMP install so you’ll need to get the IP that routes from Docker to your host IP (your physical computer). See IP of HOST available within site container? for details on how to get that particular IP.
Once you have that IP, I recommend changing your wp_remote_get call to use the IP from above rather than jpanel.local.
Let us know how that works for you…