Preface note: I invoke su and the root password before any of the below command were invoked.
I had already tried, as JMCC suggested, modifying /etc/systemd/resolved.conf, of course removing the hash sign:
DNS=8.26.56.26
FallbackDNS=8.20.247.20
#Domains=
LLMNR=no
MulticastDNS=no
DNSSEC=no
Cache=yes
DNSStubListerner=no
Then I rebooted. No effect as measured by systemd-resolve --status and by trying to browse the Internet.
The reason I didn't use IPv6 is because we block all of IPv6 everything, as a security measure (whether or not that seems like a good idea to everyone else).
Doing much the equivalent of what was suggested, I used nano to edit /etc/resolv.conf
That worked, until I rebooted and then, as indicated by /etc/resolv.conf/resolv.conf.d/head , resolv.conf got overwritten.
However, some part of JMCC's suggestion did work.
I tried chwe's suggestion because it seemed it might be a more proper way. Nope. It had the same effect as editing the connections as noted in the problem statement, which is to say it didn't work.
I've noted the Armbian in question is version 5.59. So, in response to esbeeb's suggestion, I'm downloading 5.65 in hopes I'll also see the problem go away.
In the interim, the 2nd part of JMCC's suggestion worked. I'm surprised that it did work, in light of the statement in /etc/systemd/resolved.conf,
However, it appears that rc.local is invoked after the resolver (presumably systemd-resolve) is finished, so it works.
I used nano to edit /etc/rc.local to say:
echo 'nameserver 8.26.56.26' > /etc/resolv.conf
echo 'nameserver 8.20.247.20' > /etc/resolv.conf
So, until the newest version of Armbian, available for the Libre Computer Renegade (from LoveRPi.com) is finished downloading, that is the solution.
I hope this works for everybody and greatly thank all whom contributed to this solution.
Kind regards,