Why do you say that "you need to unplug the router"? If he takes the router then yes, you have to unplug it, but if he doesn't want to take away the router you may use it further.
If the router "has to" go, there are a few cases. Your connection to ISP remains (I presume), so all you have to do is to set up your computer or buy another router and make the settings that were made on the other router.
