Sewer odours inside can show a dry catch, broken air vent

https://jeffreytdic665.cavandoragh.org/geelong-home-pipes-headaches-from-blocked-drains-to-concealed-leakages-when-to-call-a-local-plumbing-professional

Sewer odours inside can show a dry catch, split vent, or partial blockage; Geelong residential properties with large trees or older sewage system lines may require CCTV evaluations to find breaches and stop repeating scents.