Hi! Need your help
I got too much confused from forum and youtube videos without proper explanation how to setup Bonding.
I have RB2011 with latest firmware using as 1 port WAN, 2 port LAN, 3 Port NAS NIC1 , 4 port NAS NIC2.
My nas supports 802.3ad.
For now I just have internet and no problem, but when i try to go Interfaces/Bonding and link 3 and 4 ports as 802.3ad - it said "Cant create new interface - already in LAN"
So what shoud I do?

Second try I disable ports 3&4 at bridge interface and it let me add Bonding.
Is it all I need to do or anything else?
And how I can make sure if it's actually works?
My NAS (Unraid) network is setup to link 802.3ad both NIC

Thank you

After removing the ether3 and ether4 interfaces from the bridge and adding the bond interface with ether3 and ether4 as members, you have to make the bond interface a member of the bridge (or attach some IP configuration to it, depending what you actually want to happen).
To test, connect only ether3 and check you can access the files on the NAS; then connect ether4 and disconnect ether3 and try again, should work as well. Then connect both and you should see packet counters increasing on both ether3 and ether4 if you transfer files betwen the NAS and different devices. A connection to any given device is likely to stick with one of the member links of the bond when both are up, so you have to use several devices to see the traffic on both links.

Thanks Sindy!
(you have to make the bond interface a member of the bridge (or attach some IP configuration to it, depending what you actually want to happen) <--are you talking about /bridg and make new bridge - bonding?
All i did so far /bridge/ports - new port interface "bonding with attached to LAN" - is that what you mean?
So from testing if i disconnect one of the cables I should get internet anyway?
Tnx

(you have to make the bond interface a member of the bridge (or attach some IP configuration to it, depending what you actually want to happen) <--are you talking about /bridg and make new bridge - bonding?
All i did so far /bridge/ports - new port interface "bonding with attached to LAN" - is that what you mean?

Well, you've started from the middle, so I don't know how the network looked before you've decided to use the bonding, and how it should look after. One possibility is that ether3 and ether4 were members of the same bridge with some kind of spanning tree protocol running so only one of the two was active at a time, another one is that each were in a different IP subnet, maybe because you used one to access the NAS from your LAN and the other one to access it from the internet.

So describe the previous and intended configurations and I can tell you what to set up.

So from testing if i disconnect one of the cables I should get internet anyway?

Unless you access the NAS from internet or vice versa, I don't understand how disconnection of the NAS from the 'Tik (if the bonding configuration eventually turns out to be wrong) should affect whether you "get internet" or not.

I disable all bonding and want to start from scrath: this is what i have now:
Can you please check and advise me what should I do. Thanks you bro

You haven't explained how the NAS is actually connected without the bonding.

Normally, you start with a single port connection, where ether3 is connected to the opposite device and inside the Mikrotik it is a slave port of some bridge and ether4 is not connected anywhere.

So what you do in such case is you detach ether3 from the bridge, create the bond interface, make the bond a slave port of the bridge from which you have detached the ether3, and make ether3 and ether4 slaves of the bond. And after you configure the bonding on the opposite device too, you can connect the cable between ether4 and the opposite device.

See the "before" and "after" configuration below:
If you could connect the NAS to the Mikrotik using both cables while ether3 and ether4 were direct members of the same bridge, I have no idea how the opposite ports were configured on the NAS. If one of them was configured with an IP address and the other one was down it makes sense; if they had different IP addresses from the same subnet, it still kind of makes sense. But it's all speculations.