Slow/Inconsistent Internet - Santa Barbara, CA

My internet speed is very slow and inconsistent. I'm paying for the best available package for my address (300 MBPS) and I haven't received anything close to it for more than 30 minutes at a time. It's always disconnecting me or being very slow.

I know it's not an equipment issue as I've restarted my modem numerous times, I've bought new coaxial cables/ethernet cords, I've tightened the cables to the max, I've tried connecting on multiple devices and always face the same issues, my modem is in the next room and was perfect before COVID.

I'm pretty sure it's a Cox infrastructure issue as pre-covid my internet was fine.