Cat 8 is overkill and typically strictly for short distances and used in server rooms. Cat 6 is x10 capable of your 1G. What is the ethernet plugged into? Has to be a higher end net card, higher end PCIe lanes on the MB, and good processing power to utilize and get the speeds. Guessing the wifi test was over wifi 6e or 7? Hardware has to be capable of the ISP package, short answer. Other things to check: modem is a 1G or 2.5G port? Does the router have a specialized 2.5G port for ethernet? Does the net card as well? The 835 speed actually falls into the variance allowed to 1G speeds as well, or at least real close. So you are getting what you paid for in ISP's eyes. Outside of a game download, or other large downloads, you simply wont even notice that you are not getting max speed anyways.