UFEI - refind says gentoo-kernel is invalid

[Zucca]

So I have this Dell T7810.
Gentoo minimal boots fine with it.

However after installing refind, it cannot find it (refind), says no bootable disks found.
I entered BIOS/UEFI setting and rechecked that the boot entry was there.
So I resorted to copy refind -directory in ESP to the /boot (in ESP) and renamed refind_x64.efi to bootx64.efi And it worked! YAY! But when trying to boot kernel from it... it says the kernel image is invalid.
I use (unaltered) gentoo-kernel. It has the exact same "grep STUB" settings as the kernel from minimal live.
The only difference is the boot manager.
This blog post indicates the possibility, that rEFInd actually just didn't find the kernel... but it still, however, created boot entries for the exact kernel. I even tried manually specifying the kernel (prepended an "\"), but the error was the same.
I've used rEFInd since I switched to UEFI systems. This must be a configuration error. Right? Although there might be some issues with the UEFI itself in this machine, as it couldn't load rEFInd from ESP's /EFI/refind/refind_64.efi but from the default location it did.

I'm now looking at how to update the motherboard firmware/UEFI/BIOS... maybe it helps?

But I wanted to ask if anyone has experienced similar problems and how they've solved it?
_________________
..: Zucca :..

[sMueggli]

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[Zucca]