[SOLVED] Some Port Forwarding Rules Work, Some don't

[skylight1]

Hi there,

I am attempting to forward a port on my ASUS RT-AC68U. The router is configured in normal wireless router mode and handles DHCP for my network. It's connected to an AT&T provided PACE 5268AC which is configured to bridge mode, sending all traffic to the ASUS router. The ASUS router sees its WAN address as my public IP, so I know it's working and it's not on a double NAT. All internet functions work fine on the network, minus the ports I need to open for specific applications. I have assigned a static IP to the system in question shown below.

On the ASUS router, I have one port forward already configured for a Plex Media Server, and this port is successfully forwarding and works normally. If I check the port on a website like https://portchecker.co/, I can see that the port is open.

The problem is with a Valheim dedicated server which needs ports 2456, 2457, and 2458 open. I have tried these three with commas separated and with colon, but the port never opens and I can't connect to the server. I can't telnet to this port, and when I connect to the valheim server in-game with the local IP, it works. On the machine hosting the service, I also tried disabling the Windows Firewall which did not change the behavior.

Any ideas on why one port forward rule is working, but not the other?

Thanks in advance!

 

[kanewolf]

First thing I would recommend is switching to Merlin firmware -- https://www.asuswrt-merlin.net/

That looks like the correct syntax for a port range based on the very bottom of this page -- https://www.asus.com/support/FAQ/114093/

 

[skylight1]

Thanks for the reply kanewolf! I can certainly give that a try, but I'm actually about to upgrade to a new ASUS router that supports AX and is not yet compatible with Merlin. I certainly hope the firmware of the router isn't the issue here, and that I simply missed something in my configuration of the Pace or ASUS devices or something like that.

Do you have anything else you'd suggest checking or trying besides Merlin for the time being?

Thank you!

 

[kanewolf]

Thanks for the reply kanewolf! I can certainly give that a try, but I'm actually about to upgrade to a new ASUS router that supports AX and is not yet compatible with Merlin. I certainly hope the firmware of the router isn't the issue here, and that I simply missed something in my configuration of the Pace or ASUS devices or something like that.

Do you have anything else you'd suggest checking or trying besides Merlin for the time being?

Thank you!

Do you have a valid public IP address on that router? Does the WAN status match https://whatsmyip.com/ ?

 

[skylight1]

Yes, my public IP shown on the internet is the same as the WAN IP shown on the router's main page - both shown below. It's not a 10. or 192.168 local address.

The mode on my Pace router from AT&T is technically called DMZPlus mode - my understanding is that when this mode is enabled, any firewall items on the Pace box are no longer applicable as it's passing all traffic through to the ASUS router - here's the verbatim on the setting -

Allow all applications (DMZplus mode) - Set the selected computer in DMZplus mode. All inbound traffic, except traffic which has been specifically assigned to another computer using the "Allow individual applications" feature, will automatically be directed to this computer. The DMZplus-enabled computer is less secure because all unassigned firewall ports are opened for that computer.

Note: On LAN devices which have a Private IP address, once DMZplus mode is selected and you click save, the system will issue a new IP address to the selected computer. The computer must be set to DHCP mode to receive the new IP address from the system, and you must reboot the computer. If you are changing DMZplus mode from one computer to another computer, you must reboot both computers.

Is there any chance firewall rules on the Pace box are still being applied to network traffic?

 

[bill001g]

Could be a problem with the software running the game. Have you check that there actually is a program listening on the ports you have forwarded.

 

[skylight1]

Thank you bill001g. I did a hard reset on both the Pace and ASUS routers and re-configured, and had the same symptoms. From there I determined it must be an issue with the Valheim dedicated server, and it was not actively listening on that port which is why the port checker was not showing it as open despite it being properly forwarded. External users on the internet could connect to my server with my public IP and port, and I had to connect to the same server using my local IP. Just some quirkiness with an indie game I guess.

Thank you both so much for your time and help! Immensely appreciated.