@Artapel it's maximum rate between the powerline devices of 600 Mbps. You are limited to 100 Mbps between powerline device and the device connected to it by Ethernet. If the powerline device has multiple Ethernet ports, each will get max of 100 Mbps.

For a single port device 600 is still better than 400 as you would be more likely to see close to 100 Mbps over your electric wiring, unless your wiring was absolutely optimal.

@dunxd I understand that, and if the packaging said that the per port limit was 100Mbps i would be fine with that. But it does not, you have to look in detail at the specs of the individual unit in order to find that. Even with that being said, I assume this product is intended more for households trying to extend the internet connection, and since the internet connection port is also 100Mbps the 600Mbps is a theoretical impossibility. It is like saying you can have 63 GB/s data transfer because you use PCIe 5. If I buy a product that claims 600Mbps I expect to at least theoretically be able to use it at that speed. (Not by buying another 5/6 units)

I did not expect a perfect 600Mbps, and the TP utility says ~320Mbps, but I have a 150Mbps line, and I expected to reach that easily.

I don't know that I agree exactly.

It is saying it can support up to 600 Mbps on the entire PowerLine network, not 600 Mbps out of each port (or even in total on a single device).

I'm not sure there are any PowerLine (or WiFi for that matter) that have clear packaging about the actual possible throughput possible on their devices - it's buried in the small print. However, if you buy AV600 devices from TP-Link, Netgear etc. they are all going to have roughly the same limitation.

All that said, I bought TP-Link PowerLine equipment that says it has Gigabit Ethernet ports, but my computers can only detect them as 100baseT.  Edit: I discovered that some of my computers were connecting using 4 core network cable, which does not support Gigabit ethernet.  In switching for proper CAT5e cables, gigabit worked correctly.