Server-manager not accessible and network connection lost

Yes, the general Informationen I found too; but not error specifically.
For me, it sounds like a new upcoming hardware problem, because my former installation was easy.
I will analyze it deeper.

Does any principle restriction exist to use my hardware or is she well supported by Red-hot/Centos?

It is my second attempt with Nethserver…

If the hardware problem persists I think about an alternative system:

http://fit-pc.com/wiki/index.php/Intel:_Installing_Linux_Mint_18

Is this system supported by Centos/Nethserver?