Struggle to connect to elasticsearch from apps

Hi everyone,

I'm facing an issue with my apps when I try to connect to my Elastic cluster. first of all, do you guys have ever found this error?
before that, I want you to know my cluster first:
Version: 8.13.2
HTTPS: enabled, self-signed certificate, and the node certificate is intended for all data nodes (so, you know if you run openssl x509 -text -noout -in elk-cert.crt you will find all 3 data node IP's below)
App: .NET


> ```
> Invalid Elasticsearch response built from a unsuccessful () low level call on POST: /my-index/_search # Audit trail of this API call: - [1] PingFailure: Node: https://192.168.14.175:9200/ Exception: PipelineException Took: 00:00:05.0175811 - [2] PingFailure: Node: https://192.168.14.174:9200/ Exception: PipelineException Took: 00:00:04.9988055 - [3] PingFailure: Node: https://192.168.14.176:9200/ Exception: PipelineException Took: 00:00:05.0002285 - [4] MaxRetriesReached: - [5] FailedOverAllNodes:
> ```

from that error, I can ensure that my app server is connected to each of the data nodes in my cluster and I have tested it. FYI, this error doesn't appear continuously but something that makes me want to blow my head is when this error occurs, there's nothing in the elastic log. I already tried to use the CA fingerprint and it's getting worse, I got something in the log that says "unknown_ca". previously, I used the data node-1 certificate fingerprint in the code.

can you help me with this, please? or you have something to ask about? don't hesitate

Thank you