Drain odours inside can suggest a dry trap, cracked vent

https://share.relay.edu/eportfolios/217/tom-cruise/tips-on-keeping-your-plumbing-system-properly-maintained

Sewage system odours inside can show a completely dry trap, fractured air vent, or partial clog; Geelong homes with big trees or older drain lines may need CCTV evaluations to locate breaches and protect against persisting smells.