i have tried hicare method mentioned above, also checked the early adaptors, but still no update. i have the "latest" stock firmware L29C636B183 installed
First check if the regio of your Mate 9 is the same of where you are now.
If not, download "Opera VPN" and set the right region. (C636 is Signapore)
Download Firmware Finder for Huawei.
Go to Wi-Fi settings.
Push and hold down your current Wi-Fi connection.
Push "Adjust netwerk" (or something like that. Not "Forget network")
Select "Avanced options"
Proxy "Manualy"
Hostname "localhost"
Port 8080
Proxy ?? "localhost"
Save
Start Firmware Finder and (this is important!!) push "+ Add model"
(Do not choose the model FF automaticly show.)
Type: MHA-L29 8.0.0.
Select the newest FullOTA-MF-PV for your region (C636)
Push "IN-APP PROXY" and "Ok".
Goto "check for system updates" in your phonesettings.
Now you can see there is an update. Start the update and push "pause".
Scroll your screen downwards and stop the Proxy app.
Go back to the download and resume the download.
It worked for me!