@ben-coyle2 I would suggest next trying to isolate whether issue is nginx proxy or nodebb app server side. Since your install is listening to port 4567 on all interfaces, what happens if you try to connect to it directly? Browse about a bit and see if you get those errors?
Nginx can be tricky for the uninitiated. Maybe you have some knob tweaked just not quite right there?
Frustrating. Fer' sure, fer' sure. The thing is, many, many have gone before you and succeeded following the trail laid out in the docs. Hence, it behooves us to backtrack and figure out where the fcsk' we made a wrong turn.
And in final analysis.... maybe easiest to blow that vm away and start over fresh, minding extra attention to crossing all our i's and dotting all out t's..... than investing yet more effort delving deeper down this rabbit hole.....