I have a 300mbps plan with Specturm and my PC is connected throught ethernet but when I use discord images load for a long time and while playing online games my ping is bad. Using a intern speed test if shows I get much higher download speeds than my plan and about 10 mbps upload speeds.
And have you tried turning off the wifi to see that you are set up for hard wire? I had a friend who plugged in ethernet but I was not convinced that he was running on the wire as he was also very slow speeds. We turned off the WiFi and his internet stopped until restarted and then used the cable exclusively. Pretyt long odds that is the issue but thought I would share…