In working with the AWS C++ SDK I ran into an issue where trying to execute a PutObjectRequest complains that it is "unable to connect to endpoint" when uploaded more than ~400KB. 

```
Aws::Client::ClientConfiguration clientConfig;
clientConfig.scheme = Aws::Http::Scheme::HTTPS;
clientConfig.region = Aws::Region::US_EAST_1;

Aws::S3::S3Client s3Client(clientConfig);

Aws::S3::Model::PutObjectRequest putObjectRequest;
putObjectRequest.SetBucket("mybucket");
putObjectRequest.SetKey("mykey");

typedef boost::iostreams::basic_array_source<char> Device;
boost::iostreams::stream_buffer<Device> stmbuf(compressedData, dataSize);
std::iostream *stm = new std::iostream(&stmbuf);

putObjectRequest.SetBody(std::shared_ptr<Aws::IOStream>(stm));
putObjectRequest.SetContentLength(dataSize);

Aws::S3::Model::PutObjectOutcome outcome = s3Client.PutObject(putObjectRequest);

```

As long as my data is less than ~400KB it gets uploaded into a file on S3 but beyond that it is unable to connect to endpoint. I should be able to upload up to 5GB in one PutObjectRequest.

Any thoughts?

Edit:

Responding to @JonathanHenson's comment, the AWS log shows this timeout error repeatedly:

```
[DEBUG] 2016-08-04 13:42:03 AWSClient [0x700000081000] Request Successfully signed
[TRACE] 2016-08-04 13:42:03 CurlHttpClient [0x700000081000] Making request to https://s3.amazonaws.com/mybucket/myfile
[TRACE] 2016-08-04 13:42:03 CurlHttpClient [0x700000081000] Including headers:
[TRACE] 2016-08-04 13:42:03 CurlHttpClient [0x700000081000] content-length: 3151261
[TRACE] 2016-08-04 13:42:03 CurlHttpClient [0x700000081000] content-type: binary/octet-stream
[TRACE] 2016-08-04 13:42:03 CurlHttpClient [0x700000081000] host: s3.amazonaws.com
[TRACE] 2016-08-04 13:42:03 CurlHttpClient [0x700000081000] user-agent: aws-sdk-cpp/0.13.9 Darwin/15.6.0 x86_64
[DEBUG] 2016-08-04 13:42:03 CurlHandleContainer [0x700000081000] Attempting to acquire curl connection.
[DEBUG] 2016-08-04 13:42:03 CurlHandleContainer [0x700000081000] Returning connection handle 0x10b09cc00
[DEBUG] 2016-08-04 13:42:03 CurlHttpClient [0x700000081000] Obtained connection handle 0x10b09cc00
[TRACE] 2016-08-04 13:42:03 CurlHttpClient [0x700000081000] HTTP/1.1 100 Continue

[TRACE] 2016-08-04 13:42:03 CurlHttpClient [0x700000081000] 

[ERROR] 2016-08-04 13:42:06 CurlHttpClient [0x700000081000] Curl returned error code 28
[DEBUG] 2016-08-04 13:42:06 CurlHandleContainer [0x700000081000] Releasing curl handle 0x10b09cc00
[DEBUG] 2016-08-04 13:42:06 CurlHandleContainer [0x700000081000] Notifying waiting threads.
[DEBUG] 2016-08-04 13:42:06 AWSClient [0x700000081000] Request returned error. Attempting to generate appropriate error codes from response
[WARN] 2016-08-04 13:42:06 AWSClient [0x700000081000] Request failed, now waiting 12800 ms before attempting again.
[DEBUG] 2016-08-04 13:42:19 InstanceProfileCredentialsProvider [0x700000081000] Checking if latest credential pull has expired.

```