Ok....as a thought. I think you started off on the wrong foot. The dog associates the bell with food, not toilet. This maybe hard to change.
I suggest. DO NOT feed when the dog rings the bell. Next, when he rings the bell take him out for a loo trip. Be sure to give a treat at the bell ring. Also give a treat when the dogs does his loo business. It doesn't matter if it is feeding time, take him out. The treats only need to be small, just big enough for a smell and taste.
Most dogs are opportunistic eaters. Meaning they will eat anytime food is available or offered. This is why "free" feeding can easily lead to obese dogs and the practice is not recommended.
I suggest. DO NOT feed when the dog rings the bell. Next, when he rings the bell take him out for a loo trip. Be sure to give a treat at the bell ring. Also give a treat when the dogs does his loo business. It doesn't matter if it is feeding time, take him out. The treats only need to be small, just big enough for a smell and taste.
Most dogs are opportunistic eaters. Meaning they will eat anytime food is available or offered. This is why "free" feeding can easily lead to obese dogs and the practice is not recommended.