Ocelot ApiGateway unable to reach other services on Kubernetes - asp.net-core

Question

I'm working on a simple project to learn more about microservices.
I have a very simple .net core web with a single GET endpoint.
I have added a ApiGateway web app with Ocelot, and everything seems to be working fine except when I deploy to a local Kubernetes cluster.
Those are the yaml files I'm using for the deployment:
ApiGateway.yaml
kind: Pod
apiVersion: v1
metadata:
name: api-gateway
labels:
app: api-gateway
spec:
containers:
- name: api-gateway
image: apigateway:dev
---
kind: Service
apiVersion: v1
metadata:
name: api-gateway-service
spec:
selector:
app: api-gateway
ports:
- port: 80
TestService.yaml
kind: Pod
apiVersion: v1
metadata:
name: testservice
labels:
app: testservice
spec:
containers:
- name: testservice
image: testbuild:latest
---
kind: Service
apiVersion: v1
metadata:
name: testservice-service
spec:
selector:
app: testservice
ports:
- port: 80
ocelot.json
{
"ReRoutes": [
{
"DownstreamPathTemplate": "/endpoint",
"DownstreamScheme": "http",
"DownstreamHostAndPorts": [
{
"Host": "testservice-service",
"Port": 80
}
],
"UpstreamPathTemplate": "/test",
"UpstreamHttpMethod": [ "Get" ]
}
]
}
If I try to make a request with cUrl directly from the ApiGateway pod to the TestService service it works with no issue. But when I try to request it from Ocelot, it returns a 500 error, saying:
warn: Ocelot.Responder.Middleware.ResponderMiddleware[0]
requestId: 0HLUEDTNVVN26:00000002, previousRequestId: no previous request id, message: Error Code: UnableToCompleteRequestError Message: Error making http request, exception: System.Net.Http.HttpRequestException: Name or service not known
---> System.Net.Sockets.SocketException (0xFFFDFFFF): Name or service not known
Also, I tried with this https://ocelot.readthedocs.io/en/latest/features/kubernetes.html but honestly the doc is not really clear and I haven't had any success so far.
Any idea what the problem might be?
(I'm also using an Ingress resource for exposing the services, but that works with no problem so I will keep it out of this thread for now)