bought new modem but not seeing higher speeds

I recently upgraded from an Arris S33 to a Ubiquity Cable Internet to get the higher upload speeds but I am not seeing them. I still have an old Motorola Surfboard 6183 still on my account, which I think may be limiting the system. I am getting exactly 41.0 Mbps so I am hitting the throttler, not running into hardware issues. I live in Chicago, IL