Please let me know what the make and model of the TV and DVD player are, most tv’s I have seen have only one ARC port. This is where the soundbar should be connected.
I would also like to confirm you do not have an optical cable in the mix.
With the soundbar plugged into the arc port on the tv, the tv should then be configured to use ARC for audio output.
Are you currently getting your regular TV programming to come out of the soundbar?
Please let me know if there are any other cables connecting devices together that you may have not mentioned.