shaniyakov:
Once in a while we get power shortage at home.
When i turn the power on, it takes some time for the internet to recover, by that time the arduino stops searching for connection, and than i need to restart it manualy, what command can i give it to restart it automaticly, i read about watchdog but i didn't understand it very well...please help
So I assume that your Arduino loses power too...
So then you have to wait until your lan and its connection to the internet is restored.
There are methods to check to see if you have connection, and you can wait for that to happen on power-up.