I am using ubuntu 12.04 and ncftp 3.2.5

I have two modems connected to internet.

My scenario is I start the ftp upload using ncftp while this two modems are connected to internet and after the file is partially transferred i disconnect one of the modem, the ncftp just stucks for 20 mins before retrieving again. I am still unsure why it waits for 20 mins ? I dont see any parameter to config that 20 mins things. Any insight will be helpful.