AC1900 WiFi Cable Modem Router Model C7000v2 Bandwidth Capped

Hello, in an attempt to fix issue's I was having over about 2 weeks of my internet connecting poorly (I would maintain "some" connection but it would frequently be drastically a downgrade from the service I should receive, for instance I would be connected to a chat on the application Discord and I can hear others within the chat fine but my connection wouldn't allow any response) I decided to reach out to my ISP and was met with a roadblock, they were unable to help me with over the phone, but we deduced that pinging to my modem at the time was working fine through the cable. I figured since I wanted to upgrade to my own modem/router anyways I would invest in my own to see if the solution was that the modem was erroring and so I transitioned from my ISP's Altice provided modem/router to the above "AC1900 WiFi Cable Modem Router Model C7000v2" and since transitioning the connection seems much more stable but is capped at approximately 20-21 mbps instead of what I use to get with the Altice modem of approximately 200, which is what I pay for. I've ran speed tests over the past few days attempting to see if it fluctuates, but it's been very steady on download with ~21 mbps and 2 mbps on upload, which was also much higher. I scoured around to see possible fixes and mentions of new firmware potentially being the problem, but there doesn't seem to be a capability to roll back the firmware on this model and doesn't even provide QoS. Any suggestions? A technician from my ISP came out this morning and checked the connection, and also swapped the ends of the cable lines with new ends to keep them clean and attempt to problem solve on that front, the connection ended being the same right after the service reconnected to the modem and I ran the speed test.