Thanks for the note here.
You'll want to follow up with Telstra support directly for any issues you may encounter using one of their Telstra Roku-powered devices. They'll be able to assist you further and provide additional support.
As a sidenote, running a device through multiple layers of connections, including any HDMI splitter isn't typically recommended. If plugging the device directly into the soundbar, or the TV/projector is successful, this may help identify which component of your connection setup is introducing the issue.
Thanks,
Tanner