Slow upload with my own modem

I recently switched to a nighthawk 32 x 8 DOCSIS 3.1 cable (B0917R39C6) modem from the Xfinity provided gateway. Download speeds are similar, but my upload has dropped to 6-7 mbps after previously sitting around 100 mbps. I've gone through all the basic troubleshooting steps - anyone else experienced this issue? Worth a reprovisioning request?

Thanks