Soundbar disconnects from HDMI and starts D. IN ?

[Karine01]

I have a Samsung HW-K450 soundbar.

When I turn on my TV box via HDMI, the soundbar switches on and HDMI appears on the screen and the TV starts playing.
A few seconds later, a black screen appears on the TV and the soundbar's screen displays D. IN. A few seconds later, HDMI reappears on the soundbar and the TV starts playing back and continues to play. How can I prevent the sounbar from repeatedly switching from HDMI to D.IN and then back to HDMI?
I did an update of the soundbar yesterday.

[rvz8]

Hier het zelfde probleem alleen dan met een samsung hw-q950t,springt ook steeds terug van hdmi naar D.IN.

De soundbar is aan gesloten op een philips 65oled804 deze heeft de laatste update erop zitten de soundbar ook. 

[Karine01]

Does this only happen once when you turn on the TV and then it jumps back to HDMI and continues to work properly?

[rvz8]

Nee de soundbar springt steeds weer terug naar tv arc hij blijft 5 seconden op hdmi en springt dan weer terug

[BruceH]

Hi @Karine01,

How did you connect the soundbar to the TV? And which TV do you have?

[Karine01]

Tv is a LG 55EG910V.

The soundbar is connected with an HDMI cable to the HDMI arc input of the soundbar and to the HDMI input of the TV.
Can you perhaps say what the other HDMI input on the soundbar is for?

[BruceH]

@Karine01, you can find this information in the user manual. I advise to use the ARC port.