Sewer odours inside can indicate a dry catch, fractured air vent

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

Drain odours inside can show a dry catch, fractured vent, or partial clog; Geelong buildings with huge trees or older drain lines might need CCTV examinations to find invasions and avoid recurring scents.