Ethernet does not work after router factory reset.

Hello. Earlier today I factory resettled my router (a default router I got from Xfinity. XB6 Gateway according to the app). I did this to reset the admin password as I was unsure what it was and needed to check something on there. (A bridge mode for a potential router upgrade ironically)

So I set up the WiFi name and password again and now my Ethernet does not seem to work for my pc and consoles. The router was set up in the farthest part of the house from my room by either my parents or the previous owners, so any form of wireless wifi barely works. (Usually taking 30 seconds or failing to load a Firefox page.)

I am unsure how I can get the Ethernet to work again. I have tried resetting my computer, restarting the router, disconnecting and reconnecting the Ethernet cables, but nothing. I have online classes next month, as well as Christmas, so I need this fixed as soon as I can. If anyone can help, that would be appreciated.