Hi,
meanwhile, I get the impression we are dealing with two different problems:
Your case definitely sounds like the XHCI problem a patch is available for, and I believe shipping a kernel containing this patch should solve the issue.
In my case, there are no log messages in /var/log/bootlog apart from the usual ones. I only noticed the MAC and S/N of the adapter changed after rebooting into the new kernel, but that’s it.
Perhaps the aforementioned XHCI patch will solve this as well (collateral usage 
), but I won’t take that for granted. Also, in my problem seems to be related to the board, not to the USB-LAN-adapters - a device I know is working perfectly fine does not work on the affected machine either.
Thanks, and best regards,
Peter Müller