Problem with speed fusion

I have 4 peplink, one 580, one 380 and Two max 700
The 580 is connected to the 380
the first max 700 is connected to the 380
i am trying to connect the second max 700 to the 580 and the 380
it’s working with the 580 but not with the 380
It is something particular that I have to do to make it working