Sewer odours inside can indicate a dry trap, fractured vent

https://jeffreytdic665.cavandoragh.org/leading-10-typical-family-plumbing-problems-in-geelong-and-how-a-plumbing-can-deal-with-them

Sewage system odours inside can show a dry trap, cracked air vent, or partial clog; Geelong residential properties with large trees or older sewage system lines might require CCTV inspections to situate invasions and protect against repeating smells.