Unable to export metrics to elastic APM

[Depechie]

I currently have a .NET web api configured to export tracing and metrics to otel.
In the otel config yaml I have set the Elastic APM server as the exporter endpoint for traces and metrics.

But no matter what I try I always get following notification in the docker log of open telemetry:
exporterhelper/queued_retry.go:215 Exporting failed. Will retry the request after interval. {"kind": "exporter", "name": "otlp/elastic", "error": "rpc error: code = Unavailable desc = connection error: desc = \"transport: Error while dialing dial tcp 127.0.0.1:8200: connect: connection refused\"", "interval": "2.675312308s"}

End result, metrics are not shown in Kibana.
Traces are working though! So the APM connection is correct for the traces.

I pushed the complete environment here : https://github.com/Depechie/OpenTelemetryElastic