Hello MaLd0n, how are you?
Thanks for the sugestion. I added this configuration to my boot-args, and dvi-d still doesn't work. And the suspension problem is still happening. Do you have an idea what it could be? I also have the following problem: Whenever I disconnect the hdmi and connect it again, the screen doesn't come back. So I have to turn the PC off and on again to get it working again.
I don't know if this interferes, but I have an Nvidia 1060 on my motherboard, but I applied it to the boot-args to disable it. I don't know if it could be interfering in some way. Thanks for the help.