Thanks for posting this question.
To better assist you on this, just to clarify, is the machine behind a proxy? What Search tier are you leveraging?
Just to highlight, Indexing isn't a background process. A search service will balance indexing and query workloads, but if query latency is too high, you can either add capacity or identify periods of low query activity for loading an index.
As mentioned the doc, if you don’t run the Get Indexer Status within 10 minutes the code will expire and you’ll need to recreate the data source.
As an example (for Azure SQL) pointer, the default value of queryTimeout indexer configuration setting is 5-minute.
--search-indexer-troubleshooting : This article covers problems and potential resolutions when indexer results are unexpected and there is limited information to go on.
--To fetch more insights, review :#enable-resource-logging
Kindly let us know, I'll follow-up with you further.