I have received several questions regarding raspberry pi and Mosquitto . They are mainly concerned about the pi being able to handle the number of connections.
I ran my broker connection tester on my pi and got 1016 before being denied.
I was curios about this limit as it was mosquitto but the tcp daemon.
It seems that users are only allowed 1024 connections by default and so the user running mosquitto was limited you can change this see here
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