If he's rattling his cage he can damage his teeth, one of my rabbits was very obsessed with destroying his cage when he was a teenager, between 4 and 7 months, I've tried everything to stop him! What worked best was putting a large kids abacus in front of him, so before he reached his front panel he had to play a little bit so just was busy with it. I put lots of toys into his cage as well, with paper butterflies hanging from his ceilings etc, he loved them and they kept him busy, but still. I couldn't let him out of it all the time unfortunately as he was very sexually active as well and I had other rabbits and they had their time out in different times as were unfixed. He marked everything and was jumping on other cages trying to get to females and even climbed 66 cm fireguard panels, very successfully! Other thing was quite effective he'd stop rattling and chewing his bars when I put a screen in front of his cage, I have a large cork pinboard so used it, but had to cover one side of it with vinyl to make it washable, because he started spraying his walls and everything in his cage and around. Other thing that helped, to cover his cage with a blanket or light rug, when it was covered he just stopped rattling for some reason, I think maybe because he wasn't able to see what is outside so there was no point for him. I hated keeping him covered and also hated keeping him caged, he loved freedom so much.
In a few months he stopped chewing bars and I thought oh great but it wasn't great actually because he stopped eating and when I checked his teeth the bottom teeth were deformed and overgrown, I believe because he damaged them while rattling his cage.
We had to trim them a few times and it helped for a while, but still his bottom teeth were in front of his top teeth so they needed to be trimmed regularly as didn't wear out naturally. I had to feed him soaked pellets manually so he was only able to eat using his molars.
So bear in mind because some rabbits are really strong and determined when want to get out check his teeth regularly and try to drive his attention somewhere else, maybe put a playpen around his cage with vertical bars or make part of his playpen made of a heavy board or walls so he won't be able to damage his teeth. Put a cardboard sheet in front of him so he can chew on rather than his bars.