Moderate in my world just means that you are using less strict port blocking rules. In other words, you are using NAT, blocking some ports but not strictly restricting it to just web, email and such.
I suspect, but don't know for sure that it is simply doing as you have guessed. Letting you know that UPnP is turned off. It probably now considers the system as "moderate" because UPnP used to make it 'virtually' open. I say "virtually" because UPnP just kind of tricks thing out into working like it's open because it automatically connects everything as needed.
Unless you are having trouble connecting in your games, I wouldn't bother turning UPnP back on just to change the status back to Open. If it does help you to connect or connect faster for games, then I guess you have to make a choice. Denon issues or game issues.
Or invest in a router that allows you to bypass NAT altogether for a single device, as mentioned before. You will want to check with a knowledgeable friend on the same ISP to make sure that will work though. Good odds, it will.
I will look for my drawings of how IPs, NAT and ports work tonight. If nothing else, it will help you understand all those options in the XBOX network configuration screens. It can be very intimidating.
