Upload speed robbery

I pay for 1gbps upload and download speed. The download speed is sometimes at or over what I pay for, but has been as low as 300mbps at times. The upload speed has never been above 120mbps and is frequently lower than 100mbps. I am directly connected to the Xfinity provided XB8 modem via Cat6 ethernet cable. This is unacceptable as I need the speeds I pay for because I stream. If I didn't need these speeds I'd pay for a cheaper tier and save money every month.