Slow Download night of Dec. 22 through Dec 23rd

Without specific details about your AWS setup and the exact nature of the slowdown, I can't confirm if there was a specific AWS-wide issue on those dates. However, there are several possible explanations for slow S3 downloads:

1. Instance type limitations: If you're downloading from an EC2 instance, particularly smaller instance types like T-series instances, you might experience network throttling after extended periods of high network usage. These instances use a credit-based system for network performance, and once credits are exhausted, performance is throttled to baseline levels.

2. Connection tracking limits: EC2 instances have fixed connection tracking allowances based on their size. Extended periods of high network activity might exhaust this allowance.

3. Geographic distance: If you're downloading from a region far from your location (e.g., downloading from us-east-1 to Hong Kong), this can significantly impact performance due to the physical distance and network routing.

4. Network congestion: During holiday periods, there can be changes in network traffic patterns that might affect performance.

5. S3 transfer acceleration: If you weren't using S3 Transfer Acceleration, enabling this feature could help improve download speeds, especially for cross-region transfers.

To improve download speeds in the future, you could:

• Use S3 Transfer Acceleration
• Implement multipart downloads
• Upgrade to a larger instance type with better network performance
• Use a CDN like CloudFront for frequently accessed content
• Ensure your bucket is in the same region as your application

If you continue to experience issues, I'd recommend monitoring your network performance more closely and potentially reaching out to AWS Support with specific metrics about the slowdown.
Sources
EC2 Instance Network Throttled? | AWS re:Post
Downloading PDF from s3 bucket takes too much time. | AWS re:Post
The outbound speed from us-east-1 to Hong Kong is super slow. Serving website and download using Winscp is slow. The upload is normal or close to normal though. | AWS re:Post
S3 Transfer Rates Capped at 2.8mb/s ??? How Can I Speed This Up? | AWS re:Post