On second thought, try creating a new DWORD registry key under
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanmanServer\Parameters
Name the new key "DisableStrictNameChecking" and set it to one
(1).
I will do that later today and I'll let you know.
In the mean time, the solution is to name the NAS something other than NAS0.TCLC.org; I picked "NASTY.TCLC.org", and I collaterally entered "NAS0.TCLC.org = 10.1.1.80" in DNS. Everything goes back to "normal". I can make all references with "NAS0.TCLC.org", and the corrupted domain name, "NASTY.TCLC.org", just sits there fat, dumb, and happy, doing nothing to or for anybody.
ASUS reports that the issue is "known", but they don't offer any insight into "Known, how well?", of likely cause or solution. However, from my point of view, my "updated" NAS is now working [nearly] exactly the same as before the "update", so I'm not really concerned about their timing, but I am pleased to have discovered exactly the problem and had my diagnosis confirmed by ASUS. As I said, the likely solution was going to have to come from me, regardless of whatever mailing list I was using. Answering questions and providing explanations will eventually focus the field of inquiry and provide insight. In this case, it was during such a message that I realized that the "Join Domain" step was what damaged the DNS entry.
Thanks for the help,