destiny 2 cabbage error.

Looking for some network gurus. A few weeks ago i started getting the "cabbage" error code on destiny 2 when trying to load into an instance. Have never had an issue in the past few years of having my current setup. The error code states as follows, "Error code CABBAGE may occur when router settings block communications to or from Destiny services." This has dove me into weeks of troubleshooting and back and forth with not only the game studio, but xfinity as well. To eliminate the studio/game/software issue itself, i hooked the internet of my desktop to a hotspot. Game works fine. So that tells me that the issue is something related to the xfinity network, correct? I have spent hours upon hours on the phone with "support". That has led me to having my router restarted probably a few hundred times and that is about as deep as they go. They recommended i have my XB7 gateway changed out for the latest and greatest XB8 gateway, which i did and of course, that did nothing. I have spent numerous hours playing with settings such as the firewall settings (completely removing them), enabling DMZ, Enabling UPnP which was on by default in the XB7 gateway, but not in the XB8 for some reason, and forwarding ports. I even had a tech come out this past sunday, which he just kind of chuckled, said idk what you want me to do, and he was gone in probably 15 minutes. I am at a loss and i have resorted to posting on any forum i can think to post on. Any ideas from anyone. Only thing i can think to do is to go buy a non xfinity router and try that? No idea how that works. I think you have to have the gateway no matter what correct?