Sewer odours inside can indicate a dry trap, split vent

https://canvas.pasadena.edu/eportfolios/4924~6653/home/common-plumbing-leaks-that-you-may-experience-in-your-home

Sewer odours inside can indicate a completely dry catch, cracked vent, or partial clog; Geelong residential or commercial properties with big trees or older sewer lines might require CCTV assessments to situate intrusions and avoid persisting smells.