I just replaced the wax ring of a toilet leaking sewer gas, it still
stinks in the room. House is 80 original drains. What is the most likely
cause of the smell.

Can a clogged vent stack cause this smell. If so, why , it is only open
at the exit on the roof- right. Windows are sealed closed.

Or is it more likely a cracked drain pipe or bad seal of connected
drain pipes.

What is the best way of finding the leak without ripping out floors and
walls.