Chest - Stronger with Dumbbells?

I can bench press more with dumbbells than I can with a barbell.

I go bar-to-chest with a barbell and hands below my chest with dumbbells. My flat bench PRs are 155x3 with a barbell and 170x3/160x6 with dumbbells. I weigh 180 and I’m a 31 year-old recreational lifter with a desk job. I follow Best Damn 6 days a week.

I suspect my relative weakness with a barbell indicates I’m weak somewhere. What does this tell you and what do you recommend?

Nah, it could simply be that with dumbbells your shoulders/arms are in a better position than in the barbell bench. With dumbbells you don’t have to use a perfetly pronated grip like you do on the bar: you have more freedom of movement. It could simply be that in the barbell bench the grip is not as efficient as the one you use on dumbbells.