Not able to get full screen on 4K TV

I have tried everything but not sure why Volumio is not taking the full screen on my 4K Television. I have attached some images for reference.

I am currently using Allo Boss 2 Signature Player which has HDMI output which support upto 4K 60 FPS and I am using a Mini HDMI Cable for the same but not sure what is going wrong that I am not able to get the full screen and by the way this is happening for both Volumio as well as Moode. Kindly suggest. I have already tried this –

sudo nano /boot/userconfig.txt

Add to the bottom:
disable_overscan=1

CTRL+O
CTRL + X

sudo reboot

the peppy plugin has a max layout 1920 x 1080
that’s not a 4k resolution that’s why you don’t have a filled screen…

Issue Resolved

to enable 4k you have to have this in /boot/config.txt

hdmi_enable_4kp60=1

nice that you found it my resolution goes till 1920 x 1080 so could not test any.