I've been there. Try relocating the feeder to a shaded area - bees seem less keen on it. Going for a feeder with built-in bee guards worked wonders for me. And for ants, create a moat around the feeder using water or petroleum jelly. Also, consider hiring a pest removal service if things persist. I had a yellow jacket nest in my yard, and these guys were a great help -
https://www.richlandpestbee.com/stinging-insect-control/yellow-jackets/. Good luck!