I'm so lost. The point of all of this is to make a secure connection to your router from a galaxy far, far away. When you connect to your wife's hotspot on your phone, you are connecting to the phone's LAN. When you use your openvpn app on your phone, your phone is going out to through her phone to some cell tower and thence to the internet. From there it looks like it is coming back through your modem and then to the Asus router, just as it would if you were connecting from that galaxy far, far away.I did a test with my wife's hotspot on her phone.. I connected to it via wifi and I was able to use OpenVpn app... so there's got to be something in my wifi/router settings that's blocking the connection?
The same is true if you are using your cell phone internet connection. You are going out to a tower in the outer world and coming back in from your modem. So that is working fine.
When you say
are you connecting to your router's LAN over Wi-fi and then trying to connect to the router's OpenVPN server? Why would you want to do that? That's a loopback issue..if I connect to my wifi, the OpenVpn app won't connect...
Loopback should be working, but it could be a problem with the server starting on the right interface. You might enter into the custom configuration box
local [yourddnsname].asuscomm.com. That will bind the server just to the wan side.
If that doesn't work, I would write down all your settings and reset the router to factory defaults and reenter all your settings.