I have a NAS that is connected to my home router. I used to be able to access that NAS via my laptop (running Windows 8.1) when I connect to my home router too.
Recently, I am not able to do so. I am not sure when exactly and I have not tinkered with my home router's configuration. There is also no change in my network's topology.
However, I am able to access my NAS if I connect to a VPN first, for example using Cyber Ghost. I've tried disabling my laptop's firewall and flushing the dns but nothing works. I also have the exact problem for some websites.
What could be causing this problem and how can I fix it?
EDIT Following from the comment by dsolimano, I noticed that in order to access my NAS when I am connected to by local network, I need to type its local IP address. All this while I've been trying to access it by its url which is tied to the IP address assigned by my ISP (I use port forwarding so that the router redirects to my NAS).
Does this mean I have a problem with my router configuration? I've not tinkered with the router configuration but I did update the NAS a few times so is it possible that one of the updates made my existing router configuration invalid?