Winver 20H2 19042.685 Windows 10 Pro

My problem is that sometimes port forwarding just doesn't work and I cannot figure out why. I have several ports being forwarded on my network for things like Plex, game servers, NAS's and the like and over the years and from experience I just expect when setting up port forwarding that my modem or router is going to give me hoops to jump through when it should be a simple process.

Let me provide one specific port problem I am bumping into. Port 2456-2458. I am simply trying to forward these ports to one Windows 10 PC that I am using as a server. The steps I take is this...

1. Login to my router.
2. Select the Port Forward or Virtual Server section depending on the router.
3. Add my internal and external ports for both UDP and TCP. So for a range of ports I would type out 2456-2458 for internal start and end, and 2456-2458 for external start and end.
4. If any firewall rules needed to be applied to the Windows Firewall I would add them to the inbound and outbound.
5. Done.

In a perfect world that would be it. But when I test the ports using a website like canyouseeme.org it'll say the ports are closed. So then the troubleshooting begins. I restart the modem and router, that doesn't work. I check all my port forwarding settings. I go into my modem and make sure all traffic is being allowed to my router. My other ports that I have been forwarding for some time show as open and working fine but why not this new port I am trying to forward? So at this point I spend hours troubleshooting and maybe it just starts working randomly, wondering why it just started working, or I never get it to work so I give up.

Here is my network layout.

1. ATT Modem/gateway. I have it setup to basically be a modem. I turned off all wireless radio's and have it forwarding all traffic to my router. I have to tick router behind router or allow all traffic through, select DMZ and select the router in the list that it has discovered. This was done years ago and it works great. This modem uses a 192.168.1.1 IP scheme.

2. Taotronics wifi mesh is my router. 3 nodes total. Takes care of all my port forwarding, firewall and connected devices. Uses an IP scheme of 192.168.0.1.

My only complaint with this setup is that it is sometimes hard to to get into the modems UI because of the different IP schemes but it's still doable. I am also wondering if this is the cause of some port forwarding problems I have. Again, I have the modem setup to forward all traffic to the router and the modems firewall is turned off so all the traffic just flows effortlessly to the router.

So at the end of the day I am still occasionally experiencing port forward problems when trying to forward new ports and I just feel like this shouldn't be this difficult and I am hoping someone can pinpoint what I am doing wrong.

Thank you