Black Screen Channels

Hello,
I have two customers using an Mag254 getting black screen on all the channels.
The Portal is loading fine and they can see the channels but when they try to play them, it is black, no sound and no image.

I tried many resets on reseller portal, generate new router, changing - removing MAC address and Activating country lock = Same issue, no difference.
-No changes on the configuration have been made on their boxes.
-We did the update for the MAG to the new version (August 2018)
-I contacted the [email protected] and they told me that they did the reset and to restart the box = same issue, no difference. I replied them 3 times advising them that the issue persist for the last two days and they don't answer on this.
-I unplugged the box for many hours and same issue
-I tried the box on another location and same issue

Can anyone give me a suggestion or do someone had the same issue ?

Thank you,