The most common cause of buffering is the result of slow internet connection. This may be because of low internet speed or other users hogging the bandwidth in your house. Do you have lots of users in your home? Disconnect them all and try again
The second and more logical reason is that you are using Wi-Fi, it doesn’t matter how fast your internet is…Wi-Fi as whole is slow and unreliable. it just is…. You should avoid using it when possible
Directly connect to your router using an ethernet cable or to a powerline adaptor.
If not possible, try moving the box closer to the router.
Change your WI-FI channel. To avoid interference with nearby devices.