Having never used this software before, my guess would be your VPS provider is limiting the upload speed of the VPS. The data would be uploaded slowly to you, which means your download speed is limited as the client.
Meanwhile the upload speed is reported as being high enough, since the VPS can download your data at 50mbit/s, as this cap is higher.
From what I’ve seen others post, he got silver because of his teammate. If his solo performance was used to score him, he’d’ve gotten gold.