Slower speeds after Spectrum changed out equipment - Time Warner Internet

This question is about "Slower speeds after Spectrum changed out equipment", with Time Warner Cable internet and apps. Hi I was having periodic dropped WIFI and Spectrum tech surmised the adapter in my Technicolor combo modem/router was failing. The technician came out and switched my equipment for the "newest" equipment consisting of a separate modem and router setup (Hitron Modem and Askey Wave 2 routher). I have always had three pieces of equipment (2TVs and a Desktop) hardwired via ethernet. Prior to the change they were getting speeds of between 80 and 100 pretty consistently. After the change they are lucky to get 40....mostly between25 and 35!! Wifi is working fine with speeds of 200+. Oddly enough, If I take a laptop to the router and direct connect via ethernet it will also get speeds of 200+. The technicians came back to do further testing and couldnt come up with an answer other than the wiring in the wall must have a problem or is substandard. I still have to question why it was getting much faster speeds prior to the equipment change. My only deduction is that there must some compatibility issue with the home wiring in my walls that is not optimal with the new router?? Any ideas to fix? Thanks

Slower speeds after Spectrum changed out equipment?