If the gurgle happens when you run a bath or the washing machine discharges, the shared run downstream is restricted. If it happens on its own, particularly in windy weather, the soil vent pipe at roof level may be blocked by leaves or a bird's nest.
Gurgling accompanied by a smell is the same story with the trap seal being pulled out — once the water seal in the trap is lost, sewer gas comes into the room.
This is the cheapest possible moment to deal with a drain problem. A jetting visit now costs a fraction of a sewage clean-up later.