Hey, its a bit of a late post, but thought you might like to know. Also putting it down for the record in case anyone made the same mistake as I did. I think I managed to fix it for good. My static IP was previously done through Windows network configs. I just swapped methods today and set it through my router's network menus instead, assigning its public IP to my PC. With this done and the Cone UDP binding to 3074 removed, the game has stabilized with an open NAT. Guess that kind of explains it for a whole bunch of games in the past too.

Ho, finally managed to get in via telnet because of an obscure years-old comment somewhere that mentioned where to look for the correct password. Just... forgot to check the bind list before entering in the unbind for 3074, so I have no idea if that was actually there in the first place or not. Will report back if the game has stabilized.

I've seen that post before during launch period, unfortunately I don't have the correct login credentials for that method to work. It seems to have been changed from the defaults. I'll have to try and acquire it if it turns out that this issue doesn't get resolved by Bungie (or mysteriously by itself, as some things go...). Thanks for the reminder of where that post is in any case. Couldn't find it recently.

You're welcome. What I have been doing is creating a mobile hotspot on my PC, then I connect my console to that Wi-fi. The error doesn't appear for several hours.

Well, that would be really easy if I were on console... Still, you're getting them after few hours. Its not something Bungie should leave alone unless there's seriously nothing they can do and these router brands are just borked.