SER9 dual monitor problem

Lubos

I have new Beelink SER9, 32GB RAM, 2TB HDD and I have problem with connection of second monitor. First one connected to HDMI works well, second one connected to DP not working. Both monitors working well on my old PC therefore problem is in SER9. I cleared CMOS based on instructions in other post, but no effect.
SN:BHX375FH70123
SER9Pro-L-321TBVK0W64PRO-DP/XA
Can somebody help me?

support4

Hi there
If the DP port is 1.4 Version, please buy an active DP1.4 to HMDI2.1 cable ,
You can search this cable on amazon
StarTech.com 6ft (2m) DisplayPort to HDMI Adapter Cable,
8K 60Hz, 4K 144Hz, HDR10, DP 1.4 to HDMI 2.1 Active Video Converter, DisplayPort Desktop to HDMI Monitor