I wanted a way to wirelessly display / “cast” the output of my laptop, running Linux, to a remote display.

Basically, an HDMI cable without the cable.

Over the weekend, I bought a device described as

Wireless HDMI Transmitter and Receiver, 1080P Wireless HDMI Extender Support 2.4/5GHz Wireless Mirror Screen Streaming for TV Streaming, Meeting Streaming, 50M/ 165FT Streaming Video Receiver (White)

Product link

It works.

It genuinely is plug-and-play

It does not require an app / any software on the machines at either end.

It does not require pairing.

One connector is marked “TX” (for transmit), and one is marked “RX” (for receive).

There’s a diagram on the box, and a small instruction manual, for those for whom TX/RX is not self-explanatory.

You plug the transmit device (HDMI and USB) into your source system, and the receive device (HDMI and USB) into your receiver.

It works with Linux

Specifically, Debian 12, stable and testing.

The USB device does indeed appear to be power only. At least, it did not appear in lsusb, or with udevadm monitor --kernel --property --subsystem-match=usb

The packaging does not mention Linux, but, in my experience at least, it does “just work”.

I haven’t managed to get it to display GRUB, perhaps because it needs the laptop on to power the device (assuming you are using one of the laptop’s USB ports) and that, by the time the device has powered up and established the link, GRUB has been and gone.

It was fine displaying the pre-boot LUKS decryption screen.

In GNOME’s “Displays” settings, when connected to my JVC TV, it showed “Disguise Technologies 49"”, at 60Hz.

Video and audio

Audio passed through from my laptop to the TV I used for testing, without need for interference from me.

I tested it with YouTube, in Firefox. The audio sync was fine; it was perfectly watchable.

I have not tried DRM’d content, as I don’t have any to hand.

There is no noticeable lag

I was very impressed.

There was no noticeable lag, when creating a link between a laptop and a TV in the same room, over a distance of about 2.5m.

It felt “real time”, in terms of moving the trackpad on the laptop and watching the cursor move on the screen.

More than that, or trying to go through walls, I’ve no idea.

It work with (some) USB-C adapters/hubs

The device comes in two parts - the two ends - and each end has an HDMI plug and a USB-A plug (to power it).

I have tried it with a powered USB-C hub, plugging both the HDMI connector and the USB connector into the same hub. (By “powered”, I mean that I had a USB-C power input into the hub, which also powered the computer…)

That worked.

Without power, it did not work.

Or, rather, it worked intermittently - it would sometimes display the desktop/work, and sometimes it would not.

I have also tried it using the laptop’s HDMI port, and with a simple USB-A to USB-C (or is that USB-C to USB-A?) adapter.

This was just about doable, length-wise, since the HDMI port on my laptop is on the other side of the chassis to the USB-C ports.

This worked too.

So there are options for people who like/want USB-C, but it requires an adapter or hub, and it might be fussy about the hub / whether it requires power.

What it is like

It is two adapters, joined by a bit of cable.

It’s neatly packaged, with its own small (if bulky) carry case, and adapters for micro-HDMI and micro-USB (but not USB-C).

Somehow, it feels feels cheap, but I can’t put my finger on it, or give any sensible answer as to how it might change that.

It’s a couple of cables and a bit of Wi-Fi witchcraft.

I don’t know how secure it is

The packaging says that it works

Through the point to point connection between transmitter and receivere by WIFI 5G

I think that that means a 5Ghz point-to-point Wi-Fi link, since it has nothing to do with the cellular 5G. (The product description mentions 2.4Ghz. I don’t know why.)

How these devices are paired, I’ve no idea.

I didn’t have to do anything; I just plugged them in, and they worked. Which is part of the joy of them.

Could I buy another set, or another receiver, and eavesdrop on the connection? No idea. I’m not willing to spend another £60 to find out.

Could someone intercept the Wi-Fi transmissions, and recreate the image? Also no idea.

I suspect that someone would already have to be trying to spy on me for this to be problematic, and then I’ve probably got other problems anyway.

Not bad for £70

At £70, it is neither cheap nor expensive.

An HDMI cable is cheaper, and probably more reliable, and also heavier/bulkier for anything over a 0.5m length.

It’s a bit annoying that it requires a USB power source, but not the end of the world.

I’m happy with it, and I reckon I’ll get good use out of it.

Update

You can buy something very similar for much less on AliExpress.