Hi there and welcome!
Usually waking that often at night is either discomfort or often overtiredness. If these NW have always been the same it probably is routine related.
Ok so a couple of things I can see from your day.
His first nap is 30 minutes, that often happens if a LO is overtired (OT). Have you tried giving him a slightly shorter A time to see if he naps longer? At this point you would want to be working towards dropping that 3rd nap and getting 2 longer ones
All about the 3-2 transition- 5/6 monthsAlso after that 3rd nap which is also short he's doing a full 3hr A which could be making him OT come the end of the day. It might be worthwhile trying to get him to bed earlier whilst he's short napping to see if it helps catch him up a bit.
Is he an independent sleeper at nap and bedtime? If he's not it might be a good time to start working on it as it could help reduce some of the wakings or at least get you some more sleep if he can resettle himself.