I have a Dell Inspiron 3542. I recently upgraded my router to speeds of 100 MBPS. When I checked through "Speedtest" ,while connected to WiFi it only marked up to 40 or so. Then I connected it to the Ethernet, same thing.
I called the provider, the technician did the same and his computer went up to 110 MBPS!!
I've googled this and found that if I uninstall an app called "Smartbite" it would solved all my problems but it didn't. It improved a bit but still.
I have a Dell Inspiron 3542. I have re-installed drivers, ran Dell Assistant but nothing.
It isn't a hardware problem since WiFi and Ethernet are separate systems and both are capable of handling much higher speeds. I suspect it is a Windows 10 problem but I am at a loss.
The router is connected directly to the outside source. I had the internet provider come into my house. He did everything by the book. He used his laptop, measure amplitude etc. He checked my computer while connected to WiFi and also thru Ethernet.