Upload very slow A few things to consider:
1. Just because you have a 2 Gbit upstream connection, does not mean you are going to get close to that speed when backing up. You can use this Amazon test page to see what your performance is with and without transfer acceleration:
https://s3-accelerate-speedtest.s3-accelerate.amazonaws.com/en/accelerate-speed-comparsion.html
2. You are backing up to a region far from the source data which introduces additional latencyand reduces performance. if you can, I'd recommend you consider using either a local region or use S3 Transfer Acceleration if all other recommendations below do not result in the desired performance
2. I see you have Logging set to High, which is not recommended unless you are instructed to do so by Support for logging purposes. It will generate a lot of local IO as it writes out detailed log information. Please return to the normal level
3. You are backing up a network share, which introduces additional overhead when compared to backing up locally attached storage.
4. You did not mention how many files are being backed up and their average size, but you will find performance to be much better when backing up many files if you use the new backup format as opposed to the legacy format. The legacy format backs up each file as single cloud objects. The new backup format combines files into larger archives which reduces IO considerably