@josmar Make sure you are running the application as an administrator. It is very possible that the application May not work with a version of Windows after Windows 10 1904. you can do a search...

@Sleater14 FYI, They have pushed an update from July... version 1.4.2 https://www.tp-link.com/us/support/download/deco-m9-plus/#Firmware

@e3henri Sorry this reply is late, I just upgraded to the Deco m9 a few days ago... After about an hour researching, I found that a manual update is possible, but it requires accessing the command...