As per IspyIsail suggestion to do a failsafe reset and retest, I attempted to perform a "Restore Default Configuration".
I was not successful, so I decided to re-install the same firmware "Gargoyle Version:1.7.X (Built 20150604-0528 git@e7e4e5e)" over the already installed one but without the attempt to preserve settings.
After successful re-installation, I configured only minimal settings, specific to my network.
Results after 24 hours: No reboots... Yahoo

It is possible that preserving settings from a previous firmware revision of 1.7.0 to 1.7.1 had something to do with the reboots.
Similarly, when I upgraded and preserved the settings from 1.7.1 to 1.7.X (currently installed)
Now I will proceed to slowly add more configuration settings and monitor the progress.
Updates to follow in the next 24 hours...