CvH, Eureka!
In the Tvheadend web page I set the admin user as this:
username:......................................................root
allowed networks:.........................................192.168.1.0/24
web interface:.................................................checked
user interface level:.......................................expert
persistent user interface level: ....................default
admin:..............................................................checked
streaming:.......................................................advanced, basic, HTSP
streaming profiles:.........................................audio, htsp, matroska, pass, webtv-h264-aac-matroska, webtv-h264-aacmpegts,
webtv-h264-vorbis-mp4 webtv-vp8-vorbis-webm
connection limit type:....................................All (Streaming plus DVR)
limit connections:...........................................0
video recorder:...............................................basic, failed, view, HTSP, manage all, view all
DVR configuration profiles:...........................(default profile)
minimal channel number:.............................0
maximal channel number:............................0
exclude channel tags:....................................unchecked
channel tags:...................................................empty
comment:.........................................................wizard access entry
And now it seems to work!
Should I change anything?
I want to thank your support and your fast responses!