Q&A for How to Extend a Wireless Network

Just walk around the perimeter of your house until you lose your signal. You could also check the box that the router came in and it might say its boundaries.

Do a factory reset and start over from scratch. That will reset it back to default, usually admin/password, it depends on brand though. You can find out easily with a quick online search.

Yes. A Wi-Fi extender should work even if it is a different brand from the router.

You are going to need a Wi-Fi router, and a printer. You also need a device to set up the router, such as a computer or phone. You can buy these at any electronics store, and you don't have to buy anything high end. You can then follow the directions that came with those devices to set them up. I'm assuming that you also want an internet connection, so you will have to call the local Cable or Phone company where your summer house is to get a connection set up, if you haven't already.