First I checked the addon on iPad (MrMC) and Kodi on Mac, and was working without problems.
That means the problem is in the Debian version.
Than I checked on V4K the pvr Simple Client with the same VU box and was also working. I also installed tvheadend but was too complicated to set up.
Surprisingly, one last trial with the VU addon and was working.
I don’t know what fix it, the tvheadend install, the use of the Simple Client or the twenty reboots, but now is working.
I will keep an eye on it, if happen again, maybe more lucky to point the problem.