I have the answer now thanks to help from dslr595148.
I went in and checked the firewall settings to allow Remote Desktop and it appears I had to check both boxes for "Private" and "Public" for it to work.
Although the only change I made was swapping out the old ActionTec Router to the G1100, it appears the G1100 needs both boxes checked for it to allow RDP.
Previously, I just had "Private" checked.
Does not make any sense but it works.