Best drain cleaner ever! Safe cheap and easy. (kind of fun too)
1/2 cup backing soda
1 cup cheap white vinegar
1 gallon boiling water
Something to cover drain, forces “volcano” down , a plunger works

Dump baking soda into drain, add vinegar..cover quickly …for stubborn clogs you may repeat….wait 15 minutes flush with hot water ! Gone no chemicals and it costs about 50 cents.