Connection problem

[makcum4ek]

Good afternoon, I ran into this problem: I have a device for managing a smart home.The ISP board, with a battery and a screen, so that it does not discharge quickly when I do not use it, I turn it off, but after it connects to the Mqtt server 3 times, it does not allow this device to connect anymore, if it is not difficult for you, you can tell me what the problem is and how to fix it.Thank you so much in advance!