As the poster of the original message, I can understand how frustrating your find this!
In my case the problem was compounded by the utter incompetence of Netgear’s support department. I found it interesting that when I replaced my Orbi with a Synology router it suffered from the same problem - the difference was that Synology understood the problem and were able to fix it. Unfortunately I was unable to persuade them to reveal any details, but I have my theories!
First, it is now commonplace for devices like phones, tablets and laptops to be able to establish their location by listing the routers (or, in the case or cellphones, the cellular towers) they can “see”, and referring that list to a database of known routers (and towers). This can work to some accuracy, and my iPad Mini, which has no GPS facility, can be a useful navigation aid! As I understand it there are several such geolocation databases, including ones owned by Apple and by Google.
On the Orbi the only options for setting the location were to select a geographic area, NOT a country - so Netgear clearly uses some other mechanism for determining the device’s location, almost certainly a geolocation database.
The fact that both Netgear and Synology made the same mistake seems to me to imply that the database they were using contained an error. That Netgear were able to fix the problem quickly implies to me that the Rix was to amend the database. It would be interesting to try installing an Orbi here again and see if the fix Synology made abs fixes that! 
I would suggest that the problem you are having with your Asus router is likely to be a similar error in the geolocation database. Perhaps it would be worth suggesting this to ASUS?
It is important to note that this ia not an Apple problem - only that Apple software exposes the problem in a way that apparently other software does not. There are references to full descriptions of how that works in my original post,