Opened the wall, first cut made above the U shape/S shape pipe and cleared it. Second cut made after the above and before the fall off and removed it- about 3 feet worth- it was full of sludge. Rented a snake at HD, tried all the blades and was only able to penetrate the next section about a foot before running into a blockage that felt and sounded "soft" through plenty of sludge. Snaked it for about 2 hours of and on. Wouldn't budge. Went under the house and it appears only a fall off and connection to the main waste line left. All the other drains- sink, toilets, tubs, garbage disposal, outside in the yard lines and the roof vent have been snaked and/or are working fine. WHAT NOW?? What can I use to clear this line??

second cut made after the above and before the fall off and removed it- about 3 feet worth- it was full of sludge Where was the second cut made and what's a "fall off"?

tried all the blades and was only able to penetrate the next section about a foot before running into a blockage that felt and sounded "soft" through plenty of sludge. Snaked it for about 2 hours of and on. Wouldn't budge Where are you snaking from? What cutter tip did you use? As you loosened the sludge did you flush the sludge away with hot water? The best way to clear a blockage is with a snake. Go back and try again. Good luck, Tom