Xbox One wont load games.

Hi
My xbox one (origional) has been getting slow for a while. Recently it has just started to refuse to start games. It sat on loading screens for ages or just returned to the splash screen.

I cleared the cache by holding down the button etc even though its turned off at the wall every night. This had no effect.

I did a reset (keeping the games). No effect.

I did a full reset and reloaded 2 games. No effect.

It is connected to wifi (100mbps).

Currently, the kids Lego game will load after a 10 minute wait and then play ok until the next loading screen.

FO76 mostly comes up with the 'error, took too long to load' or freezes or just returns to the splash screen. Randomly, last night i did get 20 mins of reasonable game play after changing the power setting to Energy Saving. Then it crashed and now wont load
the game.

A google search only seems to provide cache clearing and resets as options and microsoft help is just as useless.

Is time for a series X (when in stock), weird timing???!!!

Any help that isn't the default answer of 'clear the cache ' or do a reset is greatly appreciated.

:)