Can not connect to the broker: Ungraceful Disconnects from unknown clients

I started HiveMQ on my laptop as a single node service, but i can not connect to the broker. And
“Ungraceful Disconnects from unknown clients” is always printed in even.log.

I am using MQTTBox and below is how i connect:

Any one encounter this problem?

Hi @chengxiangwang,

the keep alive should be the issue here. The keep alive are 16bits so the maximum value is 65.535.

Michael from the HiveMQ team.

@michael_w Thank u! That helped me!