No Sound Firestick 4k with HD channels

[Nubber99]

I have installed NextPVR on a Tiny Thinkstation with a USB tuner, and it works perfectly. 

I have tried a IPTV file from here: https://iptv-org.github.io/iptv/countries/uk.m3u  and most of the channels work. I am geoblocked from some.

However if I try and view these channels

#EXTINF:-1 tvg-id="BBCTwo.uk@HD" tvg-logo="https://upload.wikimedia.org/wikipedia/commons/thumb/1/15/BBC_Two_logo_2021.svg/512px-BBC_Two_logo_2021.svg.png" group-title="General",BBC Two HD (1080p)
https://viamotionhsi.netplus.ch/live/eds.../bbc2.m3u8

or 

#EXTINF:-1 tvg-id="Film4.uk@HD" tvg-logo="https://i.imgur.com/MTSgoGI.png" group-title="Movies",Film4 HD (1080p)
https://viamotionhsi.netplus.ch/live/eds...film4.m3u8

Then the following happens. In a browser, I get "Streaming failed - transcoder exited" and on the android app, I get vision but no sound. I have tried setting use ffmpeg, but this has no effect.

Any suggestions?