be carefull with Bonding and Port Trunking unless you have hardware capable of handling this. A Router cannot do this due to its own intelligence and internal design. For both Bonding and Trunking you need to have a switch, an unmanaged switch or a managed switches. Details below…
Best reference of all the namings and methods behind can be found here:
http://wiki.mikrotik.com/wiki/Manual:Interface/Bonding
Active Backup, Round Robin (in the above link described as Balanced-RR), Balance-XOR and Broadcast are Bonding options that can be done with any unmanaged switch.
802.3ad (link above: LACP), Adaptive Transmit Load Balancing (ink above: balance-tlb) and Adaptive Load Balacing (ink above: balance-alb) are features where you need to have a managed switch capable of offering LACP, Link Aggregation Control Protocol. Without a managed switch and enabled LACP for the trunked ports of the NAS, the network cards of the NAS will stop working as their counterpart at switch side will not answer/reply to anything. This happened to you.
I think you don’t use a managed switch with LACP enabled.
