Jellyfin rejects IPTV m3u file

I have just installed Jellyfin on Ubuntu and it seems great. I am though experiencing a puzzle.
I enter the .m3u file details purchased by me and Jellyfin throws up an alert box saying it cannot use the URL.
I can use the exact same URL on other devices such as Kodi without issue. I am also able to insert the xml epg file without problems, which has a similar format.

http://affixx.net:8880/get.php?username=name@domain.com&password=password &type=m3u_plus&output=mpegts

Any help gratefully received.
Thank you