I don't think your original post is very clear at all. I get the same number as the post you are criticizing: 1000000/179 / 60 / 60 = 1.55 hours.
Are there other messages being processed too? Which direction are the messages going? How big are they, what do they contain, how is the data processed. Also, if you have 1 million clients how do you handle all of them arriving at around the same time? How long did it take your system to get up to 1 million connections? Also how sure are you that each micro instance is sending and receiving the messages at exactly the expected rate and is not getting overloaded. What server type are you using for your central server?
Are there other messages being processed too? Which direction are the messages going? How big are they, what do they contain, how is the data processed. Also, if you have 1 million clients how do you handle all of them arriving at around the same time? How long did it take your system to get up to 1 million connections? Also how sure are you that each micro instance is sending and receiving the messages at exactly the expected rate and is not getting overloaded. What server type are you using for your central server?