Drain odours inside can suggest a dry trap, cracked vent

https://classes.iwcc.edu/eportfolios/296/home/common-plumbing-leaks-that-occur-in-homes

Sewer odours inside can suggest a completely dry trap, fractured vent, or partial clog; Geelong properties with huge trees or older sewer lines may need CCTV evaluations to situate invasions and protect against persisting scents.