LUGOSCURO

Help!!! I'm connected to a public wireless network, but days ago the signal
started to had problems. Before the computer had strong signal, but in days
the signal is poor and when I checked Event Viewer has this errors:
-Your computer was not assigned an address from the network (by the DHCP
Server) for the Network Card with network address 00210022B763. The
following error occurred:
The semaphore timeout period has expired.. Your computer will continue to
try and obtain an address on its own from the network address (DHCP) server.
-Your computer was not assigned an address from the network (by the DHCP
Server) for the Network Card with network address 00210022B763. The
following error occurred:
The operation was canceled by the user.. Your computer will continue to try
and obtain an address on its own from the network address (DHCP) server.
Please help me.
Thanks!!!