I live on the second floor of an old apt building and the landlord is out of town.
The first floor is parking so there are no units below me.
There are five units above me though.
I ran some Key Lime peels through my disposal (Which now i have come to realize is not high powered)
and now my sink is backed up.
It is SLOWLY draining at a rate of like an ounce every 10 seconds at most.
Removed the trap, its clean.
Ran a 25 ft snake from the wall under my sink.
It goes into the wall and makes a turn towards the stack.
It hits the elbow at the stack and wont go any farther.
(I assume its not a Y joint)
The stack is cast iron till it gets to the parking garage below me.
It is then has a Fernco that converts it to pvc just below the ceiling of the garage.
I tapped the pipe and its empty, so I am pretty sure my clog is between that fernco and my unit.
The fernco joint is about 2 feet below where my line taps into the stack.
The cleanout is at the bottom of the stack about 10 feet below the fernco and I only have a cheap hardware store snake which I imagine will be WAY too small to work in a 4" pipe.
Are there any chemicals or tricks that work on citrus peels?
if they went through whole they are about the size of quarters.
If I have to call my landlord to have a plumber come out I'm going to see a huge hike in my rent renewal next month so I want to try to deal with it on my own.

Call a licensed local plumber, have the drain cleaned and pay the plumber. Done.