Well...in order to access the game you need to have some sort of internet connection. I dont know how you did it without it in the past, but yes.
I could be wrong and I will slightly surprised, but last I checked you need some sort of internet connection.
Having a router wouldn't matter if, as Hakumi said, you have some sort of internet. Whether it be router, ethernet cable, wireless hotspot, etc. I'm curious, what method are you using to provide internet? Clearly you have it if you're posting on this forum, unless you're posting from your phone or using internet at another location.