The TCP stack can give you that info if you are lucky in your topography but generally you cannot rely on this working 100%. The way I solve it is to send "noo

The TCP stack can give you that info if you are lucky in your topography but generally you cannot rely on this working 100%. The way I solve it is to send "noop" messages at regular intervals so that the socket write will return -1 and then I know something is off and reconnect.