internet speed not as advertised

I have had  300mbps service  for over a year now. Recently I started checking the speed and it hasnt crossed 95mbps even once. I have spoken with 3 agents and none of them have been able to fix the issue. I also had a person come home and change the cable from the pole to the house. 

All the 3 agents I have chatted with go thru the same routine of diagnostics and leave the chat by saying sorry and that they would escalate it to the advanced team. I havent received any calls from the advanced team. 

I have checked speeds using an ethernet cable connected directly to the modem. The speeds are no different than testing the speed using wifi. 

One person told me that my modem is Docsis 3.0 and I should buy a 3.1. 

3.1 is clearly for speeds at or above 1gb. That is neither the service I have nor is it even closer to what I get.  I dont believe that the modem is my problem. 

Any help is greatly appreciated.