Upon arriving smell wasn't present after running water for about 5 minutes strong odor came out, I sold a camera run to see what can be found bur nothing concerning was found in main line, I ran camera in vent pipe clean out located in exterior wall, and found that there was a large gap in the vent pipe and pipe was offset, she stated she's had foundation issues before and new cracks appeared in wall which was why she suspected pipe may be broken. After running camera determined vent detached need tunnel to fix customer paid half