Hello,
This behavior is way lower-level than what Hibernate Search handles. It’s implemented in the Apache HTTP client, used by the Elasticsearch REST client, which Hibernate Search uses. So I’m afraid you’re not going to find experts here.
However, that also means other people that don’t even use Hibernate Search, but only use the Apache HTTP client, have also encountered your problem. I’d suggest you look in that direction?
As to Hibernate Search, if you need to configure the underlying Apache HTTP client in details, you can refer to this post. Be aware that it’s an SPI, with fewer compatibility guarantees than API and it may change incompatibly in future releases.