Talking about a total infrastructure breakdown?
“Well stocked cabin”, would be good for a few weeks to a month. I’ll give you two months.
Guns, now that is what it will all come down to.
Even if you have a gun and can shoot. Hopefully there is plenty to hunt and you know how to hunt. There’s fishing too.
Depending on how many people show up at your cabin, you will see how quickly “all” those supplies disappear.
Now that I know I might just show up. :-)
Eventually, and quickly. Other people that are hungrier then you will be showing up at your door.
That gun is going to be needed not only to kill for food. But for survival. If you can’t bring yourself to possibly and eventually kill your neighbor or friend.
Then you are back to a month or so.