RBR750 Shows Offline After FW Update

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Tnknights wrote:
A simple port scan showed all ports to the router was blocked. After the fix, ports 80 and 443 are open. A more intense scan show more ports open.

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This illustrates how terminology affects discussions.  Ports being blocked and ports being open are two different concepts.

In general, the term "blocked" means that the router has prevented data from passing through the router.  Netgear routers do not block attempts to reach other devices unless the user has deliberately created blocks using the Security "Block Services" menu.

Ports are described as being open, closed, or stealth depending on how the router treats a connection attempt to itself.

• open generally means that the router accepts a connection attempt to the router.
• closed means that the router actively rejects the connection attempt by sending back a rejection message.
• stealth means that the router does not respond at all to a connection attempt.

There is an excellent discussion of these descriptions at Gibson Research: https://www.grc.com/su/portstatusinfo.htm 

You are entirely correct that the router is supposed to accept connections on a number of ports:

• Port 53 because it is a DNS server
• Port 80 for the unsecured web interface
• Port 443 for the secured version of the web interface (with that damn self-signed SSL Certificate)
• Port 631, the Internet Printing Protocol - which "beats me" because I do not think printers can be attached to Orbi routers.
• Port 20005, which has something to do with German Telecom.

The problem that caused so much discussion on the forum is that Netgear's firmware update made the router stop accepting connections on ports 80 and 443.