@Eumno 

I've got my M9 Plus upgraded with firmware 1.5.6. I have Deco M9 Plus V2, in Canada, my ISP is Rogers. 

I did not receive firmware upgrade notification, but ran "Update Deco" from Deco app and it appeared there. 

@Alexandre.

Huh. That's weird and unfair. Lol! Kidding.

I don't have the update on my app and it's updated as always. The router's support page doesn't show the new firmware either.

Thanks, though!

@Eumno 

Open www.whatismyip.com in browser on smartphone where your Deco app is installed, connected by WiFi to your Deco mesh, and check what Web page says after "My IP Location:"

Perhaps, you are using VPN or somehow your IP is not listed as Canadian or US.

If all is fine with that IP address and it reports Canada, then there will be something for TP-Link Support to look at.

I don't think it has something to do with VPN, even though I'm not using one on any of my devices. It should be based on the router, not the device where the Deco app is installed.

It's okay now. I manually updated it by downloading the file from the US support page.

Thanks again.