XB8 Modem/Router can't connect via ethernet

A week ago, I got an upgrade from XB7 to XB8 modem/router and what used to work perfectly fine with both wifi and ethernet, now has a problem with connecting via ethernet. The issue is that its only certain things that dont work on ethernet. Every 5 minutes, it disconnects from the ethernet and starts to be really slow and stops working. This is most notable on games such as Fortnite, Overwatch, Valorant, and League of Legends. When i play these games, I get disconnected from the servers every 5 minutes and its unplayable. Playing on Wifi works perfectly fine but playing on ethernet is basically going offline every 5 minutes.

The XB7 router/modem that i had prior to the new XB8 worked perfectly. Ethernet worked well and wifi as well. It only started to act up once i got this new XB8 router/modem. I tried different ethernet cables as well and have restarted multiple times. I have also gone through support to ask for help everyday and have not ended up fixing it. The down and up speed on speedtests also show that its a little slower than it should be and is the same exact speed on wifi and ethernet. I have tried to research some fixes but I ended up with almost nothing to fix it. The most common was to update my firmware. I would like help on this since its been a week and I am currently thinking about just downgrading to the XB7 again so I have no more issues.