Help with Sxt as CPE BRIDGE

in some cases I just use the SXT in bridge with no IP set, which I find odd about it is when to set bridge interfaces and remove the IP I lose the access via WinBox on port ether1 and wlan1
why it happens when still have physical connection with the board?
to recover the access i need to reset the SXT and start over again.

thanks

You can use mac-access
http://wiki.mikrotik.com/wiki/MAC_access

already tried it!!!