Using Arduino uno + ethernet shield WIZ5100 with ext. switch (problems)

Hi to all developers :wink:

In my case, I have Arduino UNO + Wiz 5100 shield (ethernet shield) connected with LAN cable to external Linksys 5 port workgroup switch (EZXS55W model).

At the first time when I power on the Arduino I can ping the Arduino from my PC but.. If I change the LAN cable to other switch port then I can't ping Arduino anymore (even if I power on and off the arduino module)..

Is there a solution for this case?