I looked into the router settings, looking for any traffic that is being blocked and wasn't able to find anything that caught my attention. I also went into DHCP reservation and released each static IP I had assigned. As I was going through each of my IP assigned devices and refreshing the webpage for my Netgear router, I noticed that at one point ALL devices connected to my network showed up as being a wired connection which couldn't be possible as most devices are wireless!
At this point I knew that there was something wonky going on with my router and thus I factory reset it. I configured my router as it was previously leaving everything to DHCP. Then I systematically connected all of my wired devices and let my router assign IP addresses. Once my UNRAID server was back up and running, I thought I'd check the Pi-Hole WebUI once again. VIOLA!!!! I could access the WebUI from ALL of my devices. I then started to re-assigned static IP addresses to the devices that had static IP's before and now everything is working as it should....What a pain in the ass!
HOW FRUSTRATING!!!!! I never thought that the router was the issue because everything seemed to be connecting and communicating as it should, or so I thought. Live and learn and not all things are as they seem.
I want to say thank you to each of you that provided input along the way to help me troubleshoot this issue. Thank you, thank you, thank you! This UNRAID community is such a tremendous help. As I grow and learn this system and all of the things associated with it, no matter how frustrating, I will definitely contribute to helping others along the way!