It could be a lot of things, and there are a lot of things to try.
From the naps it doesn't sound like it, but could he be overtired? If he's only sleeping 8 hours per night he might be, though, even with good naps. Consider putting him down a little earlier, especially if he hasn't had his third nap? Or getting more sleep during the day? Overtiredness causes early waking.
It sounds like he is getting a lot of attention in the night, which could be reainforcing the wake-ups. Do you need to change his nappy when he wakes? If it is just wet, I would leave it as that could be waking him up too much.
Is he crying while you try to get him back to sleep? Can you leave him to just see if he sorts himself out? (We did shush-pat with DD till we couldn't see straight but when we left her for short intervals she sorted herself out much faster, with much less crying.) Our DD was older when we tried this -- I don't know if it's appropriate for such a young baby, but I don't see the harm in trying for a few minutes. Or, if he isn't crying, can you steal another hour of sleep while he plays in his cot?
If you don't think he's hungry, this could just be a habit. (Sounds like it, from the regularity.) Giving him a feed that you don't think he needs could be training him to wake at that time. Can you try wake-to-sleep? I haven't used it but others have had great success. (There are lots of threads on this, including one going on right now.)
Frankly, we tried all kinds of methods (for long periods, consistently, etc.) but we have had the best success with just leaving DD to sort herself out. She is eleven months and I still feed her once in the night. I go to her if she is teething or unwell, and I never leave her to cry for more than a few minutes, but she finds it much easier to get back to sleep without my help. Some babies are too stimulated by the parent coming in to get back to sleep. It isn't what I expected but it has resulted in fewer tears in our house.
Good luck.