You need to make sure you have correctly defined endpoints and services. That way Kubernetes will redirect requests from inside the pod to the desired outside IP. It is well described in this answer which I am posting as a community wiki here:

Create Endpoints that will forward traffic to your desire external IP address (your local machine). You can directly connect using Endpoints but according to Google Cloud best practice (doc) is to access it through a Service

Create your Endpoints

kind: Endpoints
apiVersion: v1
metadata:
 name: local-ip
subsets:
 - addresses:
     - ip: 10.240.0.4  # IP of your desire end point
   ports:
     - port: 27017     # Port that you want to access Then create you `Service`

kind: Service
apiVersion: v1
metadata:
 name: local-ip
Spec:
 type: ClusterIP
 ports:
 - port: 27017
   targetPort: 27017

Now you can call external http service using the Service name. In this case loal-ip like any other internal service of minikube.

Please let me know if that helped.