The Huawei EC6108V8 set top box (STB) of TM UniFi HyppTV comes pre-installed with YouTube app that is not functioning, even though you've successfully make use of WiFi to connect the STB to the Internet.
Anyhow, I've installed YouTube for Android TV version 1.3.8 that can functioning well in the Huawei EC6108V8 STB.
You probably can't find this app in the pre-installed Google Play Store running in the Huawei EC6108V8 STB of UniFi HyppTV. You need to make use of the pre-installed web browser in the STB and visit to the URL below to download and install the YouTube for Android TV app:
Note that the pre-installed YouTube is a system app and you can't easily uninstall it. After installing YouTube for Android TV version 1.3.8, you will have 2 different YouTube app in the My Applications screen of the STB. Luckily they have different icon, so you can easily differentiate between them.
You might probably also be interested to read about:
http://voyager8.blogspot.my/2016/01/installed-youtube-for-android-tv-138-in.html
