unhelpful `AlgoliaUnreachableHostException` error

I have a dictionary with records that I'm trying to use to generate an index. But when trying to do

```python
request_options = {
"autoGenerateObjectIDIfNotExist":True,
}

index.replace_all_objects(records, request_options)
```

I get

```python-traceback
raise AlgoliaUnreachableHostException("Unreachable hosts")
algoliasearch.exceptions.AlgoliaUnreachableHostException: Unreachable hosts
```

But if I try a dummy example where records is `[{"test": "test"}]` things work. It is unclear to me what's happening, because the error message is not helpful.

For the record:
- each record size are <10KB
- the `records` list has only 821 objects.

I've tried adding read and write timeouts but it doesn't seem to help.

```python
request_options = {
"autoGenerateObjectIDIfNotExist":True,
"readTimeout": 300,
"writeTimeout": 300,
}
```

How do I debug the issue?

- Algolia Client Version:
`algoliasearch 3.0.0 pypi_0 pypi`

- Language Version:
Python 3.10.13

No source file or test is named in the issue. Start by reproducing the failure with the provided 821-record input and trace where AlgoliaUnreachableHostException is raised; compare that path with the working one-record example. Done means the failure exposes a useful, actionable cause instead of only reporting unreachable hosts.

Written by the indexing model from the issue text.