Large config - ssh behaviour

Using an NCCM tool to collect the config from our fortinet. A weird behaviour was seen from the fortinet device , wherein it sends keepalive ssh packets to the client ,after outputting 25% of the ssh command . Then terminates the session as it doesn't recieve response for the keepalive from the client .

Weird part is other devices in the network doesnt do this and outputs the whole config . While this perticular device after sending a perticular number of lines waits for keepalive response(send 60 seconds apart) and waits for the client to respond with an ssh packet and then sent the rest of the config .

Any thoughts?