Many routers have firewalls even for the LAN. Since a router's NAT system is a natural firewall to the internet you have to ponder why folk turn on a firewall to their LAN. Your choice. Here I turned off my Archer's firewall.
Bob
Let me briefly describe my network:
I have a TP-link Archer D5 router acting as a wireless router connected to gigaset sx763 router acting as a modem.
To the router by ethernet I have connected a Seagate Central NAS (3TB version) and a d-link powerline 308AV adapter.
If I connect my PC to the router using wifi I can access everything on the NAS and configure and do whatever I want.
If however I connect via ethernet or powerline (310 AV) I can access the internet and any usb attached to the router but I can't access the NAS.
The error I get is: The specified network name is not available.
Central uses a static IP outside of the dhcp range and responds to a ping using wifi and ethernet.
I have tried 4PC's using xp,vista and windows 7 (32 and 64 bit) but it can't be seen via android (on powerline) or wdtv.
I would really appreciate any help/advice as I really tried hard and would hate to leave it not working.
Any ideas would be appreciated.
Thank you very much.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic