How to block external access to nas on port 80 behind the router?

Question

Access rights

Good afternoon.
Behind the netgear wnr-3500l router is a NAS d-link 320l. There is an external ip, yesterday I suddenly discovered that through it, through port 80, you can get to the web interface of the NAS. In the NAS settings, I did not find anything that contributes to opening access not by local ip; I didn’t forward port 80 on the router, moreover, the dlink also took 8080 for itself, so now I can’t open the remote control of the router either (well, or on a different port).
Questions, actually, two:
1. how to close access to nas from the outside?
2. How did this access open at all without port forwarding?

Answer 1

Elementary.
When setting up the NAS, you checked the box: "Automatically open ports for UPnP"
And the router most likely has UPnP support enabled. Well, your NAS has automatically configured the necessary forwarding on the router.
What to do?
Disable UPnP. Remove forwards.
Here's roughly what you did: docs.qnap.ru/$files/docs/nas/index.html?auto_route... Remove the
unnecessary here: portforward.com/english/routers/port_forwarding/Ne...