We had a bad egg eating problem and I've been able to stop it for the most part. We occasionally come out to an eaten egg but it's usually my fault for not collecting often enough or not keeping dummy eggs in the nest box.
What I did was make sure they have lots of calcium so their shells are strong. I also layer a washable nest box liner under a hay liner off Amazon so there's extra cushion in there.
I have wooden eggs in each nest box and dark curtains to keep the light out. This way if they do peck at any eggs they're more likely to peck a wooden egg and give up.
I also collect eggs multiple times a day. The longer an egg sits out there the more likely they will get curious.
Free ranging and giving enrichment in the run helps too. I tried the roll away nest boxes and mustard/hot sauce eggs - the nest boxes were too small and they ate the mustard eggs just the same