I use my cluserboard as a docker swarm, works pretty nice. See my post above about the solution i found with the custom u-boot version. I just burn armbian to a micro sdcard and then dd the custom u-boot to the card and everything works fine.
The second link from the jan willies github explains how to do this and doing a diff from his github shows the changes he has to make to u-boot. I dont know if this can be submitted upstream to u-boot, i wish i knew a lot more about u-boot.
So this is a u-boot problem.
on a totally off topic note, the clusterboard and sopine modules are better performing than the raspberry pi modules and any backplane board i have found for them and way cheaper (the modules are about the same price but $99 for the backplane with Gb ethernet is a great deal and it is matx form factor so you can actually mount it in a case).
Thanks,
Sean