It could be several things.
It could be that your router and your ISP are having problems. Reboot your router to see if it gets a new connection from your ISP. Then check the settings in the router to make sure it is set to give out IP addresses on your local network. And, of course, each device on your network should be set to get it's own IP address from your router.'
Unless you want to specifically set an IP address for a device like your printer.