Nextdns Setup On Android Device (tablet)

I am using an Android 11 device as a hotspot.

Now, I want to use a Nextdns custom dns server on the Android 11 device and other devices with which I use the Internet via the hotspot.

I also use Netguard firewall (VPN) on all android devices.

ANDROID 5 DEVICE: Nextdns custom dns server NOT WORKING

I entered the same DNS SERVER IPv4 IP ADDRESSES I used for the os x device, then, I clicked save, but, when I do so, I can no longer browse the Internet. IPv4 address, Gateway, Network prefix length, and DNS 1 and DNS 2 values can be entered; all are pre-populated with greyed out values. I entered the pre-polulated greyed out value for everything, EXCEPT DNS 1 AND DNS 2.

Can anyone tell me why Nextdns custom dns server does not work on the Android 5 device when I do the aforementioned?

ANDROID 11 DEVICE: Nextdns custom dns server working

I entered the hostname (*****.dns.nextdns.io), provided by next dns, in the PRIVATE DNS setting of the Android 11 device.

OS X DEVICE: Nextdns custom dns server working

In "Network Preferences" I entered the two DNS SERVER IPv4 IP ADDRESSES, provided by next dns, in the "DNS Servers" list of the DNS setting (tab).

IPv4 IP addresses I used for DNS 1 and DNS 2
45.**.**.***
45.**.**.***