Knowing the model number and ISP is necessary for this one.
If remote management is on, you can just enter the Router's WAN IP address and remote management port number to access
Ex. 172.124.11.9:8080
Knowing the ISP is also to verify if you are getting an exact public WAN IP address necessary for remote management.
If you are getting a private IP address from the modem to your router, then it will not work.
The AC1200 D-Link router is at my mother in law's in Asia. She has no idea which ISP she's with. Her now deceased husband set things up for her years ago. When I was there a few months ago, everything was working fine. When I returned back to the US, I realized I disabled SSID and I want to re-enable it. However, I can't do it even though when I was in Asia, I was able to access the router remotely (while on the same home network) within the home using these instructions:
The port number used to access the DIR-822 is used in the URL. Example:
http://x.x.x.x:8080 where x.x.x.x is the Internet IP address of the DIR822 and 8080 is the port used for the web management interface. If
you enable HTTPS Server, you must enter https:// as part of the URL to access the router remotely
My guess is maybe the static IP address is the issue. AFAIK, that's not a "private" IP address any more than a dynamic IP address is. Then again, I only have cable internet and I have a modem/router combo. Additionally, I can't ping it or even do a tracert using the static IP address but I was able to when I was connected to the apartment network. The IP address I have is correct too.