I found an open port on a "Kartina Quattro" (https://www.kartina.tv/article/247-kartina-quattro). It's a device for watching russian TV channels.
The port number is 31337 and the Service is called Elite.
After some research I found out that this port and servicename are often used by hackers.
I asked the support of the vendor and they only said that the ports 27000-32000 are used for the streaming of the channels. But at the time I scanned the ports, the device was in stand-by mode.
How can I figure out if it was really hacked or it's a legit service running on it?