The card is a dual band card, but since it is working in N mode (Radio type : 802.11n means 2.4GHz) only & not in AC mode=5GHz), it could be the card (Realtek chip) is faulty & you need to replace the card. Since the card is a 1*1 TR that means only one antenna connector inside. So, you cannot probably install a better quality 2*2 MIMO AX/AC/A/B/G/N card & have to stick with similar 1TR cards. You already mentioned you have reinstalled the drivers, you can try some older drivers from ASUS https://www.asus.com/my/supportonly/x415dap/hel...
If that helps you make the radio work in 5GHz mode & shows 802.11AC in device properties.
https://youtu.be/LsMVSTDYCHk?t=61 may watch this video to change the band to 5GHz if your card giving you the option.
Remember the website I mentioned are third party sites in terms of Microsoft policy, apparently, they provide safe & accurate information, please use your own discretion browsing third party sites.