Understanding Powerline speed

Question

I am stuck in this. I own a pair of TP-Link AV500 Powerline adapters. My home electrical wiring is not the optimal for Powerline, but I must live with it.

The AV500s have a manufacturer-advertised maximum bandwidth of 500Mbps. All my LAN equipment is 1Gbps, including home gateway (no, I don't have 1Gpbs internet access, I am talking about LAN).

I connected my desktop both directly to home gateway and through Powerline using the same 1Gbps cable. When attached LAN-to-LAN I can see Windows 10 reporting 1Gpbs as expected.

If I set up LAN-PWL-PWL-LAN from desktop to home gateway I see the following reported speeds.

Windows 10 reports 100Mbps on the LAN adapter, which is connected to Powerline adapter

Gateway reports 500Mbps on its LAN port to twin Powerline adapter

TP-Link's Powerline tool, on the Remote devices page, reports a rate of about 300Mbps, which is quite good according to my non-optimal electric setup.

Question: since I want to communicate with a NAS on the other side of the house that is directly attached to the Gigabit Lan network, why the heck does Windows 10 report only 100Mbps from the LAN port to the Powerline LAN port? I need more speed for internal transfers.

For experimenting these speeds, I have moved the Powerline adapters to the same place in the house and tried to swap them to my like.

I don't think that upgrading to 1Gbps Powerline adapters makes difference (I could try as soon as I have a decent refund policy from my seller)

Answer 1

I own a pair of TP-Link AV500 Powerline adapters

First a note: "AV500" is not a model number; it's a network type – short for "HomePlug AV 500" (HomePlug AV being one of several powerline networking standards).

I'm guessing you have something like a TP-Link TL-WPA4220?

Now to the main question:

why the heck does Windows 10 report only 100Mbps from the LAN port to the Powerline LAN port?

Because it is connected to an Ethernet device that's only capable of 100 Mbps.

Powerline isn't a direct Ethernet link between two adapters and doesn't directly transfer the Ethernet signalling over electric wiring. Instead, it's very much like Wi-Fi – the device speaks Ethernet on one side, HPAV or Wi-Fi on the other side, and forwards layer-2 frames between the two networks. Each network has its own speed.

Among other similarities, both HPAV and Wi-Fi are half-duplex networks over a shared medium (meaning the maximum speed is only "possible" but not guaranteeed), and you'll see the same marketing tricks as well. Remember those "Wireless-N 300" APs with only 100 Mbps Ethernet ports? Exactly the same situation here – the advertised 500 Mbps is only for the powerline side, and only under ideal conditions; it'll vary based on the number of Wi-Fi clients or HPAV adapters, as well as outside interference.

(On the other hand, Ethernet always negotiates a fixed speed which never changes while the link is up – the standards define 10 Mbps, 100 Mbps, 1 Gbps, … but you'll never see your Ethernet adapter reporting numbers like "300 Mbps" or adjusting automatically.)

Of course, traffic is limited to the slowest link, so you'll never get more than 100 Mbps from a device that has a 100 Mbps Ethernet port.

In conclusion,

I don't think that upgrading to 1Gbps Powerline adapters makes difference

Yes, it will. If you upgrade to adapters with 1 Gbps Ethernet ports, then your PC will start reporting 1 Gbps, and the actual maximum speed will now be limited by powerline instead (best case ~400 Mbps).

(You don't necessarily need to replace both at once, if at least one already has a Gigabit port – it should be possible to connect even a different manufacturer's adapter to the existing network.)