Cox internet issues in my home

I have lived in my home for 3 years. I have always had the gigablast internet with unlimited data. I have also always had issues with my speed and connection. Never getting above 300Mbps down. I have contacted customer service in the past regarding the issues nothing ever gets solved so I am posting for others to be weary. For the last 3 years I have had panoramic WiFi and over the last several months my panoramic router just keeps dropping the connection. Then it boots back up and I have to manually reset it to get my smart devices and things to connect again. I was sick of it. So I went to Best Buy and bought a new Netgear modem and a top tier router. All Docsis 3.1 capable and and gigabit download capable. I am still only getting speeds in the 300Mbps down. But at least with my new Linksys gaming router and this new modem all my devices will auto reconnect which is something they would not do before. I am super frustrated and I may just switch my ISP. I hear OEC now offers fiber in my area. I feel lied to and cheated by Cox. I have tried every speed test site out there I have disabled WiFi and connected directly to the modem and done speed test still never better than 350Mbps down. I have tried those same test at different times still no improvement. Why have I been paying for gigablast if I never get those speeds. If anyone knows of any way to resolve this issue I am open to suggestions. I am tired of having to rest my modem or router and I am tired of my connection always randomly dropping and booting back up at all time of the day and night. Any help is greatly appreciated.