Port Forwarding Issue

I feel like I'm losing my mind. I'm trying to Port Forward on my SBG7600AC2 . The program in question uses port 24872. I've tried just about everything I could find/think of, and I just can't get canyouseeme or any other port checker to detect the port as open (they just time out); on the program's end, no one is able to connect to my room. It seems that I can’t get any ports open.

Here are the steps I've taken:

• Assigned a static IP to my PC through control panel > network and sharing center - connection name > properties > TCP/IPv4 > Properties > Use the following IP address. The subnet is correct, and the Default Gateway and my assigned IP address are different. I've tried using multiple numbers within my range. I've tried a few different Preferred and Alternate DNS, including 1.1.1.1 / 1.0.0.1 and 75.75.75.75 / 75.75.75.76.

• Logged into Router and added a Port Forward for the program, using UDP (and UDP/TCP at one point), making sure that the Private IP address is my computer's IPV4 and that the inbound port and local port are 24872.

• I've also tried adding a Port Trigger for 24872.

• Added an Inbound and Outbound rule (for both TCP and UDP) for Port 24872 through my Windows Firewall. I also tried straight up disabling my firewall - neither worked.

• Disconnecting my Ethernet and seeing if I could get it to work via wifi (using a separate instance of Port Forwarding, as my Wifi Card has a different IPv4 address. I've also tried connecting to the ethernet Port Forward via wifi and vice versa with no luck.

• Downloaded a port listening tool, and used PSPing on another computer in my LAN to see if there was any activity at all. Port checking websites all come back as (port closed), and the port listening tool doesn’t react to any probes from sites like canyouseeme or GRC/ShieldsUp; although it does respond when I use PSPing and the command “ netstat -an“ on my other computer, returning with “UDP 0.0.0.0:24872”

• I’ve tried setting my external port number to a high UDP ranged number, just to try it out. Didn’t work either.

Throughout each step (and countless times at the end of all of these steps), I've tried to have someone connect to me via port 24872, and it errors out. I’ve tried resetting my router throughout each of these steps, as well. For what it's worth, I've tried opening other ports (such as 21 for FTP) and they all error out as well.

Additional Info -

Internet Provider: Xfinity

Router Model: Arris SBG7600AC2

Connected via: Ethernet

I've followed Arris' online Port Forwarding set up guide, tried a bunch of other websites, and even contacted Xfinity; nothing seems to work. Xfinity confirmed that I am not behind CGNAT, (my WAN address does match IP checking websites), and told me to contact Arris Support; however, my warranty ran out last October. I feel like the answer is simple and I'm overlooking something, but I just can't figure it out.

Could some kind soul please tell me where I'm going wrong. Thanks ahead of time.