I hate to say it but even though naps aren't great, they sound like UT night wakings
as in, not consistently having enough A time in one good chunk to help him to sleep soundly. We were getting similar until very recently, especially on nights after a four nap day. DS was ill and teething also, but it has only been since I've pushed his A times quite a bit that the chatty vocal NWs have stopped....at least for now! I know we were due the same day so if it helps, DS is now pushing 2h30 A time when rested
seems like a high A kind of boy, you might not need to go that far but I wonder if pushing him a bit would help?