Apple - How to have multiple (wireless) network profiles?
You can set up 'Locations' using System Preferences-> Network, which should do what you need.
In the Network System Preferences panel, you'll see (at the top) a pop-up menu labeled Location. It will be set to Automatic. Click that menu and choose Edit Locations...
Click the [+] button in the panel that appears. Name your new Location. Click Done.
Make sure the new Location is selected under the Location: menu, and set it up.
Then, when you need to change back to the other setup, change the location back to Automatic (or rename Automatic something more descriptive). When you need to change again, switch back to your new one.