2 days ago, my ac86u suddenly lost connection and the led lights went out. power cycled the router and the lights came back up briefly but went off again after few seconds. left it overnight and tried different power adapter etc same problem.

was about to send the router back to rma but found some links that mentioned similar symptoms when a firmware upgrade went wrong.

anyway last resort, tried the firmware restoration procedure mentioned in the manual. restored successfully, then reapplied the saved settings from my backup and have it up and running within 15 mins.

no idea what caused the errors though, because i wasnt flashing the firmware or anything when it happened. probably corrupted itself during a power trip or something.

just leaving this here in case anyone face similar problems in the future.