RT-AX88U Can't See PC on this Router/Port Forwarding Not working/Web server Not Visible

[Basspig]

I replaced a Linksys router (WRT3200ACM) because after 5 years, it started rebooting frequently and cutting our internet.

The Asus router has some issues:

I can no longer see the web server from another PC on the LAN:

I've added all the port forwarding from my old router list:

But the server is no longer visible to the internet.

The web server can access the internet and can browse the web. But unlike with the Linksys router, it cannot be seen by the web.

I purchased this router on Amazon but it says "buy used from $xx" and there was no buy new option. I'm concerned this router is defective and was a returned unit.

I was able to do all these things with the Linksys router before the silicon on it started failing.

My LAN is set up like this:
Fiber ONT -> Frontier router (in DMZ)-->Asus router --> Linksys router (inner tier)

Original config before tonight was:
Fiber ONT -> Frontier router (in DMZ)-->Linsys router --> Linksys router (inner tier)

In the possibility that I've overlooked some configuration, I'm posting my issue that someone may tell me a solution to make the server visible both on the LAN and on the web again.

[Basspig]

I swapped out the Asus router and plugged my old Linksys back in and within 90 seconds, the web server is back online and I can also access all the computers on the LAN again. Had to do this or else my customers will not be able to reach my websites. This Asus router is no good. It's going back to Amazon.

[jzchen]

My question now that I think about it is how did you deal with the NAT, or double NAT?

Linksys 192.168.0.

ASUS 192.168.1.

by default.

[Basspig]

I have to set the outer tier router to a different domain else it would conflict with the inner tier router. So the first setup step was to configure the Asus for 192.168.0.1.

This configuration has worked for 5 years with my Linksys routers. I don't know what the problem is with the Asus, but I suspect it was returned and sold "used" for a reason.

[Basspig]

As I have not been able to find a solution, nor get any technical assistance with this product, I have decided to return it "defective".