I was skeptical, but a fan does seem to help
I was skeptical a fan would help anything but now I'm not. I installed an 80mm one and it does seem to increase speeds once the lower temperature stabilizes (a few hours after install). I only have the fan on low andI have it plugged in to the USB-C on the back of the gateway with a USB-C to USB adapter. Note, the 80mm fan size seems to work best as the air goes in to the gateway better versus 120mm, where some air goes outside of it. I got this fan, only about $11: https://amzn.to/3mFqaKo