Our family was staying in a Kimpton Hotel in Coopertino that offered free wireless where I encountered a problem with wireless connectivity.  My daughter’s Mac laptop could easily connect to the wireless system but my Mac laptop could not.  I called the front desk and they said there was no setup to be made.  I dug into my laptop for a considerable time trying out a number of things.  When I chose System Preferences>Network> [Then choose Airport from list] >Advanced>TCP/IP and change the option for “Configure IPv4” from “Using DHCP with manual address” to “Using DHCP” I then got it to work properly.