I have A Deco M4 and two Deco E4 with me, in the Deco app I have an option for an antivirus integration of Norton 360. I am not sure whether my routers support the antivirus integration. Plus my route

I have been facing drastic decrease of my WiFi speed, I have contacted the ISP but according to them there is something wrong with my Deco. My internet speed is 100mbps, but the speed of 2.4Ghz is 20m