We have a Netgear nighthawk r8000 and it works great for every game except destiny 2, and even then it only causes issues when we both try to load in somewhere together. Half the time it'll work fine, half the time it'll black screen both of us for about two minutes until one of us manages to load in and the other gets cabbage. I've tried changing the DNS settings on the Xboxes, I've messed with rolling back the firmware update (it seemed like this might be it but it never fully fixed the problem), even factory resetted the router, but nothing has really fixed it.
Two series x's
Posted here because cabbage is the "router shenanigans" error
Do you have UPnP set up? If not, that's why you are getting it; simply put, one Xbox uses one the network ports needed by Destiny 2 making it unavailable for the other Xbox.