Thank you!Glad to help. You reminded me why I don't use the apps. The issue with having to enable GUI access over the WAN is troubling. Ah, the IoT.
I always use VPN for the three routers I support remotely. I access the Web GUI using a browser on my Windows 10 laptop, Android Phone or iOS iPad. I wrote a post in March about setting up OpenVPN Server on AsusWRT-Merlin and how to configure the clients on iOS, Android, Windows and Mac OSx that may be of additional help.