Sewer odours inside can indicate a completely dry catch, split air vent
https://www.pitchero.com/clubs/eyelsh/news/common-plumbing-leaks-that-you-may-experience-2923600.html
Sewer odours inside can suggest a dry trap, fractured vent, or partial blockage; Geelong buildings with huge trees or older sewage system lines may require CCTV assessments to situate invasions and prevent repeating scents.