Cable modem disconnections and low speed

I just bought a new modem from cox and paid nearly $300 out of pocket at their store because I kept getting Disconnected on the old Netgear modem I had. It really hasn’t helped much, I only have two splitters on this line, but get disconnected multiple times daily and speed is erratic. I’m supposed to have gigablast but often get less than 100 mbps. The connection has become so erratic and since I work from home I’ve had to get a backup internet plan just in case. The power on many channels is around 

so could that be it? What can be done to fix it as it’s not inside my house as nothing has changed and I’ve replaced all the splitters and double checked all the cables  etc.. 

thank you