Recommended opening drywall above toilet to expose where shower venting ties into toilet vent in order to attempt to perform further snaking of showers. Opened drywall above master toilet of unit 855 C to gain access to venting for showers of both units B and C. Removed section of vent and performed snaking. Was able tile remove clog and restore proper flow to both showers. Installed a cleanout in wall to allow for future access to shower drains