Hi, i have a setup where i cannot make RB3011's troughput go over 400mbps...
It doesn't look like you can specify which switch ports will work with particular CPU. Both CPUs have connection to both switches.
And It looks like all the traffic is going through CPU1. The SFP is connected to CPU1. And ports connected to switch1 also have a lane to CPU1. The shortest path for the traffic between these does not involve CPU0. In these situations, usually the CPU that is not involved with the raw traffic, gets to be more involved with the software stuff (firewall, NAT, vpn, etc). This is somewhat backed by your stats - cpu usage by firewall rules is not that much, and CPU0 is not so loaded.
You should be able to push about double on what you are seeing. Do you see any events in the log regarding the SFP?
P.S. There is no speed gain in using bonding, since the lane from the switch to each CPU is 1Gbit. Only redundancy. Though, enabling bonding will turn off the hardware offload on QCA8337 switch:
https://wiki.mikrotik.com/wiki/Manual:S ... Offloading