Review of GL.iNet Comet (GL-RM1) KVM-over-IP solution and ATX power control board

GL.iNet sent me a Comet (GL-RM1) remote KVM box for review, along with a GL-ATXPC ATX Power Control Board. I’ll start this review with an unboxing and a teardown, then I’ll use the GL.iNet Comet with a Raspberry Pi 4 SBC to control it from a web browser in the LAN and the GLKVM app from the Internet. Finally, I’ll connect the GL-ATXPC and GL-RM1 to an Orion O6 mini-ITX motherboard to test ATX power control.

GL.iNet Comet (GL-RM1) unboxing

I received a parcel with two retail boxes: one for the GL-ATXPC ATX power control board and the other for the GL-RM1 Comet Remote KVM.

The GL-RM1 ships with an HDMI cable, an Ethernet cable, a USB-A to USB-C cable for keyboard/mouse emulation, and a USB-C to USB-C cable for power, as well as a card with a QR code to connect with GL.iNet, and a getting started guide in English that also points to the online documentation.

Ports on the Comet include a USB 2.0 port for accessories like a FingerBot or the ATX power control board, an HDMI port for video input, a USB-C port for keyboard and mouse emulation, a 5V/2A USB-C port for power, and a Gigabit Ethernet RJ45 port.

From another angle, we can also see the Reset button to restore the GL-RM1 to factory settings.

Let’s open the GL-ATXPC package. The KVM-ATX-V1.0 board features a USB-C port, upgrade and reset buttons, and two 9-pin connectors for ATX power control. Other accessories include an 80cm USB-A to USB-C cable, a 30cm 9-pin wire set, a screw set, and mounting brackets.

GL.iNet GL-RM1 teardown

The bottom side of the device has some useful information, namely the device host name (glkvm.local), MAC address, serial number, and device ID.  To open the enclosure, we’ll need to remove four rubber pads and loosen four screws.

The top of the board features a Winbond W634GU6RB-11 4Gbit (512 MB) DDR3 chip and Toshiba THGBMUG6C1LBAIL 8GB eMMC 5.1 flash.

We can pull the board out with some tools to see the rest of the design. There’s an extrusion on the metal case, but it’s not really used for cooling, since there aren’t any thermal pads, probably because it’s a low-power solution, and the company figured it was not needed.

The main SoC is a Rockchip RV1126 quad-core Cortex-A7 processor designed for cameras, but here, the company leveraged its MIPI CSI input for HDMI input through a bridge. We’ll find another Winbond 512MB DDR3 chip to bring the RAM capacity to 1GB as advertised.

I suspect the chip under the metal shield is the HDMI to MIPI DSI bridge, but I could not see the markings on the chip. Ethernet is implemented through a RealTek RTL8211F gigabit Ethernet transceiver. People interested in playing around with the GL_RM1_V1.0 will also see a 4-pin UART header on the bottom left used to access the serial console.

Getting started with GL-RM1 Comet KVM IP box using a Raspberry Pi 4

So now we need a target device to connect to the GL-RM1. I’m not sure why or how, but I had a Raspberry Pi 4 housed in a KKSB case on my desk, so I went with that one…

The white cables are from 5V/5A official power adapters used to power both the Raspberry Pi 4 and GL-RM1 (only 5V/2A needed). Since the Raspberry Pi 4 does not have a standard HDMI Type-A port, I used a micro HDMI to HDMI cable instead. I also connected the provided USB-C to USB-A cable to one of the USB 2.0 ports on the Pi 4, and finally, I plugged the Ethernet cable from the kit into a switch for LAN access.

The printed user manual tells us to download the GLKVM application on the host, but sadly, it’s only available for Windows or macOS, and I’m a Ubuntu user. Luckily, the online documentation also mentions that we can access the interface from a web browser locally. Two methods are possible for remote access outside of the LAN: the aforementioned GLKVM application or Tailscale virtual private networking (VPN) solution based on WireGuard. The latter would also work on Linux.

We’re told we can connect to glkvm.local, but it’s not working on my PC, although the KVM box is clearly up and running:

So I’ll use the IP address in the web browser. It works, and the first step is to set up the admin password.

At this point, I got a white screen, and also noticed that a firmware upgrade was available from v1.1.0 release2 to v1.3.0release1. So I click the Upgrade Now button to proceed.

I will download the new firmware, flash it, and reboot. It works. At this point, I get no HDMI signal detected, which is odd, and another notification (red dot) in the top bar.

I’m now asked to upgrade from v1.3.0 release1 to v1.3.1 release2. I’m not sure why it couldn’t be done the first time, but let’s proceed again with the upgrade.

It went smoothly like the first time. I still had the “no signal” issue. I decided to switch the resolution to 1920×1080 (instead of 2560×1440), and power cycle the Raspberry Pi 4, and it worked. It was running an old Ubuntu 20.04 installation, so I decided to remove the SD card to show the Raspberry Pi 4 bootloader, or the equivalent of a BIOS on a computer, in the KVM window.

It complained about the lack of an SD card, so I inserted one preloaded with Raspberry Pi OS, and the system booted properly. I wanted to check whether 2560×1440 resolution would work, and it did.

I could remotely control the Raspberry Pi 4 as if it were connected to a monitor, launch programs, and use the keyboard and mouse normally.  Let’s go through the key settings in the GLKVM web interface.

The user can select video quality from low to ultra-high, as well as various EDID presets for displays with different resolutions and with or without audio support. It’s also possible to customize the EDID values. In the LAN, you’ll probably want to select ultra-high, and when accessing the device from the Internet, you’ll want to adjust the quality depending on the available bandwidth. Text becomes difficult to read in low quality, as you can see from the screenshot below (click to enlarge).

Audio can be enabled too, and I was expecting to hear audio through the HDMI TV’s speaker connected to my laptop (the host) when watching a YouTube video, but it did not work at first. I just realized Raspberry Pi OS was set to use the AV jack, and when I switched to HDMI input, I got audio working normally.

Other settings let the user control the keyboard, mouse, and system settings like language (English or Chinese), color mode (light or dark). Most are self-explanatory, although I was first confused by “Mouse Jiggle”, which randomly moves the mouse pointer from time to time to prevent the computer from entering sleep due to prolonged inactivity.

What I could not do was copy/paste text from the host to the target board and vice versa, but that’s where the toolbox section comes in handy…

Simply type text in the Clipboard field and click “Paste to Remote Device” to send the text. Several languages are supported, and not only English.  I was able to select Thai language and paste Thai characters, but I had to install and switch to the Thai keyboard on Raspberry Pi OS. If I try to paste Thai while the English keyboard is selected, it will send the equivalent ASCII characters instead, and for example, สวัสดี will show as “l;ylfu”, unless the Thai keyboard is selected.

Special keys may be an issue since they may be used by the host OS or the web browser, so the Toolbox section also features a list of shortcuts that the user can customize as needed. Wake on LAN is supported, but the Raspberry Pi 4 does not support this feature. GLKVM will automatically detect devices with WoL support, or you can add a device and its MAC address manually.

Finally, the access terminal section gives access to the Linux OS on the GL-RM1 KVM box.

The Accessories section is to connect an external device. We’ll try that in the next section with the ATX power control board and Orion O6 mini-ITX motherboard. The Virtual Media section gives access the the eMMC flash on the GL-RM1, and users can upload files from the host or a URL.

I uploaded an image as a first test, but the main use case is to load ISO files for OS installation. Once our files are loaded, we can click Mount to Remote to select File Sharing (Network Share) or Image Mounting (CD-ROM emulation).

After enabling File Sharing, we can access the /media/pi/GLKVM share on the target device to get to the files we’ve just uploaded.

Since the guest and host and all on the same LAN, I could also access the glkvm-11 share from my laptop.

It requires login as the root with the admin password. This gives access to the full rootfs on the GL-RM1 device.

Once we have done we can unmount the network drive and stop file sharing. If we select Image Mounting, the interface only offers us to mount as CD-Rom (maybe USB is coming soon), and then we can select the file.

It doesn’t support img files, let alone compressed img files, so I loaded a recent Lubuntu ISO. The CD-ROM was automatically mounted on Raspberry Pi OS and I could access the files in read-only mode. It’s not super useful for the Raspberry Pi 4, but that enables remote OS installation on x86 machines.

The App Center only has one app for now: Tailscale for remote access over VPN. I’ll skip that part, as I reboot into Windows 11 and use the GLKVM program for remote access later in the review.

There are also a few icons on the top right of the toolbar. Collapse toolbar, full screen, firmware check, Cloud service (download GLKVM program), Security to enable 2FA authentication, Reboot, and Logout.

Before switching to remote access, I captured a screencast to show the performance in the LAN using ultra-high video quality.

Remote access via GLKVM Windows program, 4G LTE connection

I’ll now reboot into Windows 11 to install the GLKVM program in Windows and enable Cloud Access with my laptop connected to the internet through a 4G LTE using USB tethering from my smartphone.

I first connected through the web dashboard in Windows 11 and clicked on the “Download APP” link.

From there, I installed GLKVM for Windows and started the program. I was first asked to Log In, but since I never used the GL-RM1 before, I decided to Sign Up instead.

 

I was denied because my email was already registered. Ah… So I clicked “Forget Password?” and then I received an email to reset my GoodCloud password. Ohhh. I see now. The cloud service is shared with the GoodCloud remote management service I first used with the Brume 2 router. So, no need to change the password, and I just logged in with my GoodCloud credentials.

I clicked the “+ Add Device” button, and my GL-RM1 was automatically detected since I was still on the LAN at this stage.

The program will show a list of online devices and their local IP addresses.

I clicked on it for remote access, and I was asked for the Admin password set previously.

The GLKVM program looks almost exactly the same as the web dashboard. The only extra option is the Orientation to rotate the display by 0, 90, 180, or 270°. I initially thought the resolution and bitrate, and status icons shown at the bottom were new, but they were just hidden on Firefox by a plugin I installed to show the time in different time zones.

Everything worked fine, so at this stage, I decided to disconnect the Ethernet cable and disable WiFi on my laptop, and connect it to 4G LTE using USB tethering from my phone. Here’s Ookla Speedtest results for reference:

I could connect to the Raspberry Pi 4 remotely thanks to the Cloud Service.

There is some extra lag, but it was not too bad on this connection. The screencast below shows GLKVM with ultra-high and medium video quality settings. Ultra-high is also clear, but with medium the text is blurry while scrolling and becomes readable after a few milliseconds once the screen is more of less static.

 

GL-RM1 KVM with ATX power control board and Orion O6 motherboard

While we can control the Raspberry Pi 4 remotely, if it hangs or is shut down, we are out of luck until somebody physically accesses the board to power cycle it. If you own a motherboard with ATX power control, then this can also be done remotely with the GL-ATXPC board.

The first step is to get the pinout for the front panel header of your motherboard, and wire it with the GL-ATXPC ATX power control board as shown below. I initially made a mistake because I wrongly assumed all “+” wires would be red, and all “-” wires would be black. That’s mostly true, except for the Reset+ (black) and Reset- (red) wires.

The GL-ATXPC board would typically be installed in a chassis or PC tower, so I also mounted it to the provided bracket.

Once done, we can connect the motherboard to the GL-RM1 with the provided HDMI and USB-C to USB-A cables, and connect the GL-ATXPC power control board to the USB 2.0 port on the GL-RM1 KVM box.

The Orion O6 board will boot to Debian 12 as expected, and going to the Accessories section will show the ATX Power options as the board was automatically detected.

I first tried the Power (Short Press) option. A confirmation pop-up showed up, and I clicked on Confirm.

After a few seconds, “No HDMI signal detected” was shown in the web interface, and the fan of the Orion O6 stopped. Success!

However, I clicked “Power (Short Press)” again, and nothing happened. That’s because Short Press lasts only 0.5s, and the Orion O6 requires the user to press the button a bit longer to power on. Luckily, there’s a  “Power (Long Press)” option that simulates a button press of 6.5 seconds, and this time around, I could power the Orion O6 motherboard remotely.

I wish the behavior of the power button were more customizable, as some systems require a 10-second press to force a shutdown when unresponsive. It looks like a simple firmware/software upgrade, and if even people demand it, I’m sure it will be implemented.

When I first tried the Restart option, it failed because I had wired the Reset switch incorrectly. After fixing this, it worked just fine, as you can see in the recording below.

Conclusion

GL.iNet Comet (GL-RM1) is the first KVM over IP solution I’ve reviewed, and it basically matched my expectations. I actually expected more lag, especially over a cellular data connection, but it was still relatively smooth thanks to H.264 encoding.

It works on the LAN and from the Internet, and besides video, keyboard, and mouse, HDMI audio input can also be enabled. There is a range of options for keyboard input with support for special keys and clipboard sharing. It’s also possible to load an ISO onto the GL-RM1 device to install an OS from the BIOS. Some potential downsides are the lack of a Linux program for remote access, so the only option on Linux is to set up a VPN connection with Tailscale, and I wish the clipboard were bidirectional, since right now, we can only paste text from the host to the target, but not vice versa. Some people may have hoped for PoE support, but the company offers that option with the Comet PoE model.

The ATX power control board does what it’s supposed to do, and I had no problem, apart from some incorrect wiring on my part, using it with the Orion O6 motherboard. It supports power on and off, as well as reset. If the timing of the power press could be further customized, it would also enable more use cases, like a forced power off, typically requiring a 10-second press.

I’d like to thank GL.iNet for sending the Comet (GL-RM1) KVM box for review. It can be purchased on the company’s store for $80.91 or $91.71 with the ATX power board. Alternatively, you’ll also find it on Amazon for $89.99/$102.80. If you need PoE, the Comet PoE is coming soon, and I was actually offered a sample, but we had to skip since it has yet to pass NBTC certification.

Support CNX Software! Donate via cryptocurrencies, become a Patron on Patreon, or purchase goods on Amazon or Aliexpress. We also use affiliate links in articles to earn commissions if you make a purchase after clicking on those links.