You don’t need a new router to use 2.5GbE on your NAS

While multi-gig WAN (wide area network, your connection to the outside world) sounds great, it’s entirely unnecessary right now, at least, for getting multi-gig speeds on your LAN. A LAN is a local area network, and you can easily achieve multi-gig speeds using various other methods instead of replacing your router. In fact, replacing your router is the most expensive way to achieve 2.5GbE speeds on your LAN.