I’ve got a GL-M2 board in my travel trailer; I use it with my Slate AX (GL-AXT1800). I’ve been quite happy with the GL-M2’s performance and reliability. But, I do use the Slate AX/GL-M2 combo as a backup gateway and my primary modem/cell connection is Spitz AX (GL-X3000). Long story short: I bought the Slate AX, four months later the Spitz AX was introduced and I decided to buy it, a few months afterwards I had fallen in love with the Spitz AX’s cell connectivity and decided to buy a M2 board for my Slate AX as a backup.
I’ve never used the M2 with Visible - I have used it with AT&T, KPN (and 80+ country IoT SIM out of the Netherlands), Rogers and Telus (I’m Canadian, eh?). The M2 is fairly flexible and you can adjust the TTL and MTU, and its very easy to change the IMEI to match a device that a given carrier might expect to see on its network. As the Spitz AX and the GL-M2 both use the Quectel RM520N-GL modem, posts on these forums about carrier issues with the Spitz AX will usually apply to the GL-M2 as well. In the past, there have been some issues reported (and fixed) about Verizon/Visible, so make sure to look around.
I’ve seen various GL.iNet devices for sale on Amazon, but never the M2 board. I ordered mine directly from GL.iNet’s online store - it was shipped via FedEx from Shenzen, China to Toronto, Canada in five days (technically, I ordered it on a Friday evening, it was shipped on Monday and received that Friday).
There is no official enclosure available for the GL-M2. I 3D-printed one I found here on the GL.iNet forums - and I’ve been quite happy with it: GL-M2 5G Development Board enclosure? - #9 by sharkfi
As a reminder, if you’re looking for a plug-n-play solution (i.e. connecting it to a router and the GUI automatically supports it), the GL-M2 is supported by the following GL.iNet devices: Slate AX (GL-AXT1800), Beryl AX (GL-MT3000), Brume 2 (GL-MT2500), Flint (GL-AX1800), Flint 2 (GL-MT6000)
On the Slate AX, the modem configuration in the current (stable) firmware falls somewhat behind the Spitz AX. The Spitz AX’s GUI supports display of connected bands, band locking, and tower locking - the Slate AX does not (although all these functions can be accomplished with manual AT commands).
Power-wise, the GL-M2 uses a 5.5x2.1mm barrel plug and accepts 5.5-17 volts, so it can be directly wired to an RV’s 12V system: GL-M2 Dev Board power voltage - #2 by Dipin
And, just to geek out a little bit… one future possibility I’ve been considering is to build a waterproof housing for the GL-M2, attaching it to the back of a directional panel antenna (minimizing cable loss similar to InstyConnect’s approach), and raising it on a pole with long 12V cable and USB cable to connect to the Slate AX inside.