My Router says US too (in the upper left corner), but I am in HK and bought it in HK.
However (on the Beryl AX at least), if you can use WinSCP, you can navigate to:
/etc/config/wireless
and then in that file change the Country Code for each of the 2.4G and 5G options to one that matches your country’s regulations. Note that “wireless” is a file. In WinSCP you can open it as a text file.
See here for How do I change my country code on the GL-MT1300
NOTE!! That link shows changing both Country and Region codes, but on the Beryl AX do NOT change the REGION Code, apparently the Chip doesn’t support it; change ONLY the Country Code (if you know what you’re doing).
Wifi Codes listed here: What channels are supported in both the 2.4 GHz and 5GHz band in most countries?
Country Codes in 2 Letter Format listed here: Country Codes List
btw; changing the Country Code in that file only changes the Wifi Frequencies available to you. It does NOT change the “Country” in the top LH Cnr of the WebAdmin of the device. I think the “US” device is to distinguish it from e.g. the “CN” device, which does not have a VPN function.
k.