Desktop Will Not Connect to Xfinity Modem, but Will Connect to Hotspot, No other Devices Affected

My Windows 11 desktop will not connect to my Xfinity modem. Whenever I try to connect, it says "connected, no internet". When it does connect, the internet speeds are 10x less than what I am paying for. I initially thought this was a problem with Windows, so I reset my IP configuration through CMD and Powershell but that did not work. I tried uninstalling, reinstalling, and resetting my network drivers, but that did not work. I tried uninstalling my antivirus but that did not work. I tried restarting my modem by unplugging it and plugging it back in again but that did not work. I even did a system restore of Windows 11 to a restore point that I made before I had these problems, but even this did not work.

I am unable to access my Xfinity modem through my browser with the 10.0.0.1 IP address on my desktop. I can, however, access my modem through my laptop with no issues. Every other device on my network gets the 400Mbps speeds that I am paying for except for my desktop. My desktop will connect to my mobile hotspot with zero issues. So, I have concluded it is not my desktop, because if it was, I would have the same internet issue when using my mobile hotspot. 

I would like to know what other solutions I can try? I NEED to have my desktop connected to stable internet, and the only thing I can think of is that I need to do something with my modem, or that there is a setting in my modem that got corrupted and will not connect to my desktop specifically. Again, every other device on my network gets the speed I am paying for. When connected to my mobile hotspot, my desktop has zero internet issues. What more can I do? What setting within my gateway can I change, revert, or reset, that could fix this issue? If I cannot get this issue resolved, I will be forced to switch my internet provider. I do not want to switch my internet provider, but I cannot accept these connectivity issues to my desktop.