@Lors Sadly it's the same case here.

Please go to settings -> System -> (click your main router) -> then check the CPU and memory usage.

I have been getting 100% CPU usage all the time with my Deco X50-5G and memory usage always hover above 80%.

In fact the issue of it going down throughout the day has happened since the day I bought it about half a year ago.

The error log kept showing temperature related error lines. You can access the log via the web interface.

Please check yours and update here. I'm curious.

  @Lors Try manually setting the "Carrier" setting shown in your screenshot. This fixed the same problem I was having with my X50. On mine it is set to "o2-PAYG".

  @David-TP 

yes, the light does turn red. 
 

I have upgraded to the beta firmware sent to me. Unfortunately it is still happening. 
 

I did not take a screenshot during the outage but I do remember that everything from WAN IP down was reading 0. 
 

I am also frequently getting disconnected from the Deco when this happens. My devices appear to be connected to wifi but neither the app or the web interface respond (screenshot). I have to physically unplug to reboot when this happens. 

  @Lors Hope it works. I had a unit which worked for a week on 4G without any problems, but when switched to 5G it constantly went red, normally after a few minutes. I set the carrier and it has worked now for about 9 months on 5G without any red lights.