yet another This device is not using NextDNS.

quick sitrep:

three systems, all running Kubuntu 2204 and NextDNS 1.42

All OS are up to date.

browsers WaterFox, FireFox, LibreFox report working NextDNS on two systems.

yet, on one system, FireFox, WaterFox, LibreFox complain of the above "not using" when on nextdns.io, which identifies "This device is currently using 'TerraTransit AG' as DNS resolver." (all browsers installed using either FlatPak or SNAP so ARE isolated from each other.)

(also, if i understood what i was doing on the ADMINACCOUNT, System Settings/Network, i MANUALLY set the DNS to 45.90.28.241 and 45.90.30.241; but i am uncertain as to how to get the OS to display if it is actually using these, or, which DNS settings as one could in Windows using the CLI command: ipconfig /all which would detail the OS' configured DNS)

here are CLI details of NextDNS:

=========================================

ADMINACCOUNT@5479:~$ sh -c "$(curl -sL https://nextdns.io/install)"
INFO: OS: ubuntu
INFO: GOARCH: amd64
INFO: GOOS: linux
INFO: NEXTDNS_BIN: /usr/bin/nextdns
INFO: INSTALL_RELEASE: 1.42.0
c) Configure NextDNS
r) Remove NextDNS
e) Exit
Choice (default=c): c
NextDNS Profile ID (default=#################):
Sending your devices name lets you filter analytics and logs by device.
Report device name? [Y|n]: y
Accept DNS request from other network hosts.
Setup as a router? (y/n): n
Make NextDNS CLI cache responses. This improves latency and reduces the amount
of queries sent to NextDNS.
Enable caching? [Y|n]: y
Instant refresh will force low TTL on responses sent to clients so they rely
on CLI DNS cache. This will allow changes on your NextDNS config to be applied
on your LAN hosts without having to wait for their cache to expire.
Enable instant refresh? [Y|n]: y
Changes DNS settings of the host automatically when NextDNS is started.
If you say no here, you will have to manually configure DNS to 127.0.0.1.
Automatically setup local host DNS? [Y|n]: y
NextDNS installed and started using systemd init
c) Configure NextDNS
r) Remove NextDNS
e) Exit
Choice (default=c): e

=========================================

Usage: nextdns <command> [arguments]

The commands are:

install         install service init on the system
   uninstall       uninstall service init from the system
   start           start installed service
   stop            stop installed service
   restart         restart installed service
   status          return service status
   log             show service logs
   upgrade         upgrade the cli to the latest version
   run             run the daemon
   config          manage configuration
   activate        setup the system to use NextDNS as a resolver
   deactivate      restore the resolver configuration
   discovered      display discovered clients
   cache-stats     display cache statistics
   cache-keys      dump the list of cached entries
   trace           display a stack trace dump
   version         show current version

USERACCOUNT@5479:~$ nextdns version
nextdns version 1.42.0

USERACCOUNT@5479:~$ nextdns status
running

USERACCOUNT@5479:~$ nextdns log
Error: not supported

=========================================

(not supported?)

So.

I can not provide "log" information, for, some, reason.

Also, as two of the systems are IDENTICAL OS & Hardware,

this suggests there is a specific configuration issue on the one.

I would appreciate suggestions on additional tests i can run to track-down what is amiss on the one problem system.