intel integrarted graphics (Kaby Lake) monitor stays black after boot menu


my System:
MoBo: FUJITSU /D3417-B2, BIOS V5.0.0.12 R1.8.0 for D3417-B2x
CPU/GPU: Intel Kaby Lake Xeon E3-1225v6 with Intel HD P630 Pro

When booting, boot menu is fine (efi-grub2), afterwards screen stays black.
When I configure the kernel with “nomodeset” in grub2, screen is usable, but only with a resolution 1024x768.
Native resolution is 1280x1024 (LCD Monitor Eizo FlexScan L778). The monitor has DVI-D, but is connected to the Mainboard via adapter DVI-> DP (on the DVI-Port of the mainboard the screen doesn’t even display the boot menu).

How can I achieve a resolution of 1280x1024 ? With Leap 42.2 the resolution was correct (boot without efi).

#lspci -vnn|grep -i vga
00:02.0 VGA compatible controller [0300]: Intel Corporation HD Graphics P630 [8086:591d] (rev 04) (prog-if 00 [VGA controller])

#hwinfo --gfxcard|egrep “]*Model:|]*Driver”
Driver Info #0:
Driver Status: i915 is active
Driver Activation Cmd: “modprobe i915”

Is this Leap 15.0? Did you upgrade from 42.3?

If both answers are yes, I had this issue with a similar (though not identical) computer. Mine had the 620 version of that Intel card. I was not able to boot successfully after an upgrade from 42.3, however a fresh load booted fine OTB,

Note: I was able to reuse the same /home, so the process wasn’t too painful.

Yes this is LEAP 15.0.
No, it was no upgrade, but a fresh install of LEAP 15.0 (I kept /home partition).