I used a combination of things in this thread... mostly from Oatbag's guide. TL;DR = success!
Used the Dashboard to stop the AdGuard service.
Dashboard >> Plugins >> AdGuard ... click the "
>" at the far right, scroll down and click "Stop".
Opened a Shell from the Dashboard, used the "iocage console AdGuard" command to switch from root to the AdGuard jail.
(This was before I noticed you could just go "
Dashboard >> Jails >> AdGuard ... click "
>" and scroll down and click Shell)
In Shell, I couldn't find my .yaml file using the
/usr/local/bin/ directory as noted, so I followed Dxtros cue and entered "
find / -name AdGuardHome.yaml" and found that my file was in the
/usr/local/etc/ directory instead. Made a mental note and moved on.
Next I installed nano; "
pkg install nano" and when that was finished I opened my .yaml file "
nano /usr/local/etc/AdGuardHome.yaml" and viola! Finally in where I needed to be.
Next, I went over to
https://bcrypt.online and found a very simple hash generator. I typed in my desired password, left the "cost factor" where it was, and clicked "Generate Hash". Clicked the "copy" button and went back to my TrueNAS tab.
Arrowed over to the hash line of the password, erased what was there, pasted in my copied hash and while I was there I went ahead and took the liberty of changing the user name to something other than "admin". Used
Control+O to write out the file, pressed Enter to keep the same file name, then
Control+X to exit the nano editor.
With my new credentials in place, I used the dashboard to restart both the AdGuard jail and the AdGuard service.
Dashboard >> Jails >> AdGuard, click the "
>" to expand, scroll down, click "Restart" and wait.
Dashboard >> Plugins >> AdGuard, click the "
>" to expand, scroll down, click "Restart" and wait.
Now.. fair enough to say that I probably didn't need to restart the service itself because when I restarted the jail, it restarted the service as well, but I've wasted enough time beating my head against the wall on this project, what's another 30 seconds just to be sure.
Used my browser to navigate back to the AdGuard GUI, plugged in my newly minted credentials and got right in.
Thanks to all of you who contributed to this.. I'd have never figured this stuff out on my own!