Beaglebone buildroot don't boot when the ethernet cable is connected

I’ve compiled the buildroot to the beaglebone white rev A5, this works fine, but when I try to boot with the ethernet cable connected the board doesn’t boot.
Someone knows why? or where can I look for some log file?


How about hooking up a 3v3 ftdi or similar cable to the Serial debug header, then you can let us know why.