might I have 3 different Firewalls (Windows 10/11, Netgear AC1200, McAffee from Cox Cable)

[ehGreen]

Using R6220 & trying to open  tcp port 5223 required for a LAN attached PVR (TiVo series 3).

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LAN has 25 devices (win 10s, win 11s, Chromebooks, switches, MOCA-pair, Roku , RokuTV, HP Printers, gPixel 3A & 8, gHome 'speakers')

==I 

Think there is a possibility of 3 sources for firewall settings &  my action taken:

a- Windows Defenders (done on just one PC NOT on every PC), [followed https://www.portcheckers.com/open-port-in-windows-firewall]

b- Netgear AC1200 Advanced Port Forwarding

c- some version of McAfee - supplied by Cox Cable  {not examined yet}

**

So far, the result is NOT OPENED.

Port Checker - Check Open Ports

The Port Checker tool can verify whether the ports of any internet-connected device are open or closed.

Test

[schumaku]

The first point to check is if the router does have the same valid public IP address assigned (from the ISP by DHCP) on the Internet (WAN) port and the IP address e.g. the dynamic DNS is registering and resolving to.

Your R6220 router does have public IPv4 address on it's WAN/Internet interface, or does your ISP (or in-house network service) deploy Carrier Grade NAT (RFC6598, or even worse private RFC1918) IPv4 addresses?

Compare the information shown on your router Web UI WAN/Internet port vs. a search for "what is my IP address"!

Is the R6220 connected behind another NAT router?

Any ISP side firewall provisions in place? Some ISP are operating firewall services on their infrastructure to "protect" their customers from the big unknown enemies. This can be controlled from the ISP service customer portal for your connection.