Maxtimeout Reached

Hi Everyone,
recently when I try to index a document. The request, response with max-timeout reached
after a certain point in time, and it starts indexing again.
Now, I'm trying to find the root cause of that issue. The only thing I'm able to find is one of my master nodes was down at that time. will it result in that timeout issue?
the infra details of my Elasticsearch are:
run in Kubernetes
3 data nodes - each node spec(ram 64GB memory limit 32GB) - heap size - 28GB disk size - 1TB
3 master nodes - each node spec(ram 16GB memory limit 4GB) - heap size - 4GB disk size - 10GB

How are you indexing to Elasticsearch?
What is the full error you are getting?

I'm using Nest client in C#
the method I'm using is ExecuteBulkIndexOperation

 MaxTimeoutReached:\n# OriginalException: Elasticsearch.Net.ElasticsearchClientException: 
 Maximum timeout reached while retrying request. Call: Status code 504```