Hello Yongqin,

Again, not a lot of information from the logs, but perhaps you coud give me
more information for your scenario.

Could you try to execute the down interface operation, mac assignment and
the up interface operation from command line? 
That works for me.

Maybe some synchronization issue is happening in your boot operation.
Could you provide more information about how/when you are doing the
commented operations to try to reproduce?

Best regards
José Ignacio