Pork didn't get done in time I recently made this recipe:

https://foodwishes.blogspot.com/2016/08/paper-pork-shoulder-its-wrap.html

7 lb pork shoulder, apply rub, wrap tightly in parchment and foil, roast at 225 F for 12 hours.

I cooked it in a freestanding turkey roaster and after 12 hours, plus an hour of rest, it wasn't really done -- the meat wasn't fork-tender, and the bone was still firmly attached.

I then put it in a 350 F oven for about two more hours, with another hour of rest, and was much happier.  The meat was fall-apart tender, and the bone slid right out.

But why did I have to do that?  How did I screw up?

It shouldn't matter that I used a freestanding roaster instead of a standard oven, should it?  225 degrees is 225 degrees, right?

I only had a few other thoughts:

I didn't let the meat come up to room temperature before roasting, but I don't think the recipe said to do that.  (Is that just assumed?)

The meat was sitting on a rack in the roaster, with a little bit of air space underneath, instead of sitting directly in a baking dish as in the recipe video.  Can that matter?
Based on your original question and the comments, it sounds like you simply did not make an accurate assessment of the temperature of your product and your cooker.  Low and slow is an excellent technique to make pork shoulder tender.  Your goal should be an internal temperature of about 195 F ((90C).  Estimates are that you should allow 1 to 1.5 hours per pound, but this can vary depending on the heat source and the fat and bone content of your pork.  It is best to measure the internal temperature.  As pointed out above, two things potentially "went wrong".  Either your cooker did not maintain the temperature you thought it did, and/or you pulled the pork out before it reached the desired temperature.  For best results in the future, use accurate thermometers and measure both.