This isn't the place to report kernel issues, it's really just a tracker for the IoT compose sides of things.
Anyway the DTB should be in /boot/dtb/allwinner/sun50i-a64-pine64-plus.dtb and it wouldn't boot at all without it. What kernel?

OK, will do next time. Also, I attached a file with the full dump of the boot...
I tested again on the latest nightly build Fedora-IoT-28-20180731.0.aarch64.raw.xz

Linux localhost.localdomain 4.17.9-200.fc28.aarch64 #1 SMP Mon Jul 23 21:27:04 UTC 2018 aarch64 aarch64 aarch64 GNU/Linux

The DTB you are referring to is not present, and I agree, it should not boot without it.
This is where I am getting lost: the boot has DTBo located in /boot/efi/overlays, which is identical to /usr/share/bcm283x-firmware/overlays/
and there are files in /usr/share/uboot/pine64_plus/
The one you are referring to is /usr/lib/modules/4.17.9-200.fc28.aarch64/dtb/allwinner/sun50i-a64-pine64-plus.dtb (which I was expected to be seen on the /boot)

Marc: can you give a F29 image a go and see how you get on. EG: https://kojipkgs.fedoraproject.org/compose/iot/Fedora-IoT-29-20180814.0/compose/IoT/aarch64/images/Fedora-IoT-29-20180814.0.aarch64.raw.xz

Hi Peter,
I was able to test following images:
Fedora-IoT-28-20180813.0.aarch64.raw.xz: no ethernet working
Fedora-Minimal-28-1.1.aarch64.raw.xz : working
Fedora-IoT-29-20180814.0.aarch64.raw.xz : working

Since the IoT based on 29 is working, this issue can be closed.

Thanks

So I think it's getting the DT from U-Boot, I was going to ask you to test F29 as the U-Boot there is newer so will have likely synced the DT so this makes sense. Thanks for the update. F-29 is where the changes are happening anyway.