You really need to share your router settings.There's a ton of them that can cause this. Also it's quite common that the auto detect (LAN/WAN) settings on both the NAS and router can be a cause. This happens quite often with every brand or make. So don't be disappointed and get a new router, just post your settings and fiddle around with the auto detection features of both devices. Networking is still miles away from issueless plug and play, just keep that in mind.