remote control for a Samsung android unattended device

Suddenly teamviewer doesn't allow me to connect to a S5 samsung device unattended, i was working very well several weeks ago, from remote control host in another A7 samsung device I just was conecting to the other device without problem , but since 8 days ago  it is not possible, I reinstalled the app several time host and quicksupport in both devices  and now is mandatory to allow the control in the remote device, that is the problem is a unattended device.