NAD-dependent oxidoreductase with broad substrate specificity that shows both oxidative and reductive activity (in vitro). Has 17- beta-hydroxysteroid dehydrogenase activity towards various steroids (in vitro). Converts 5-alpha-androstan-3-alpha,17-beta-diol to androsterone and estradiol to estrone (in vitro). Has 3-alpha-hydroxysteroid dehydrogenase activity towards androsterone (in vitro). Has retinol dehydrogenase activity towards all-trans-retinol (in vitro). Can convert androsterone to epi-androsterone. Androsterone is first oxidized to 5-alpha-androstane-3,17-dione and then reduced to epi- andosterone. Can act on both C-19 and C-21 3-alpha-hydroxysteroids. {ECO:0000269|PubMed:10896656, ECO:0000269|PubMed:11360992, ECO:0000269|PubMed:11513953}. This is the function of HSD17B6 (hydroxysteroid 17-beta dehydrogenase 6, ENSG00000025423).