Ethernet much slower than the wifi

We have been dealing with this problem for a while. We are on the 1000mbps plan and we are getting 400mbps on wifi and only 90mbps on ethernet. The pc that is hooked up to the router we have taken to the shop recently and everything worked fine and connected to the ethernet just fine. We have also replaced the ethernet cord and updated our router to the newest one and tried all the ethernet ports. Is there something that we are missing?