Hardcoded DNS in Cellular Info (PiHole)

[Reclaimer]

Trying to set up a custom DNS on the 5g Router supplied by Three (NR5103E). I've specified my custom DNS in the  home-networking section however something keeps undermining my blacklist which I believe to be the hardcoded DNS located under 'Cellular Info'.

Is there a way to change this? Please let me know

[usernamefor31]

When I've set my NextDNS IP under the home networking option that has been passed on to devices by DHCP correctly so blocking has working correctly.

Is it not working on all devices connected?