@marcusob 

You'll benefit from Link Aggregation only when accessing the device from your LAN.

Here's a typical scenario using this feature.

@terziyski Thanks for the info. The diagram shows 2 PCs accessing the router, and the router having 2 lans to a NAS. So I can see the 2 LANs to the NAS as getting to 2GB/s but why is this aggregation ? As simply using 2 LAN cables from the router to the NAS will do exactly the same.

The PCs on the picture only have a single LAN to the router, and the router only supports 1 GB/s LAN ports, so even if the PC LAN port supports 2.5GB/s, the PC can not access more than the 1GB/s LAN output on the router.

If there were 2 LAN ports on the PC (which I have), and 2 on the router, and I could connect my PCs 2 LAN ports to the router, then I could see how 2 GB/s could be available to the PC - if you were streaming 2 different files from the router.

OR if there was a 2GB/s LAN port on the router, and I could connect one of my 2.5GB/s LAN ports to it then I could also see the 2GB/s to the NAS as useful, as then my PC could handle >1GB/s on a single LAN, so eve naccessing the same stream/file would be beneficial.

So it seems aggregation means simply having the concept of a single 2GB/s ethernet container on the router, but I dont see any point to that, as you have to use 2 cables from the router to the NAS anyway both at 1 GB/s, and everything leaving the router is 1GB/s max, as the aggregation is not to any PCs.   

marcusob wrote

So it seems aggregation means simply having the concept of a single 2GB/s ethernet container on the router, but I dont see any point to that, as you have to use 2 cables from the router to the NAS anyway both at 1 GB/s, and everything leaving the router is 1GB/s max, as the aggregation is not to any PCs.   

@marcusob 

This is just a simple example diagram.

When the PCs are connected through 5GHz wireless network to the router it would be beneficial for sure.

In the example C5400 has 2x 2167 mbps bands on its 5GHz band.