I have many PC Engines APU and APU2 (https://www.pcengines.ch/apu.htm) and i used to install on it Freebsd (actually 10.3).
I'm having a lot of difficulty installing Freebsd 11 on their sdcard: when i turn on the engine it never boot. I discovered the problem trying to install opnsense 17.1 (https://forum.opnsense.org/index.php?topic=4872.msg19180)
As i said in this report:
Using the serial com port, here is what it says on SD boot:
on apu1: "ehci_wait_td error - status=10000d40 USB transmission failed"
on apu2: "Timeout at sdcard_waitw"
When i upgrade opnsense 16.7 (freebsd 10.3) to 17.1 (freebsd 11) the problem not occur, I can reboot without problem.
APUs are AMD64 CPUs, not ARM