I do not find much of an advantage between my AR300M16-Ext and my AR300M, as the little antennas just don’t seem to help much. Trying a different long range antenna on the AR300M16-Ext did not help me. Being small, I find placement much more important then the external antennas. When I travel, I use a WIFI app on my phone to find the strongest signal in the room I’m staying in, and that is where I put my router.
If you want to go through some work, I would recommend the external Panda Long Range PAU08 USB WIFI adapter, as it gives about a 20db improvement over the internal radio in the AR300M16-ext, at a cost of less the $15.00. At my house I go from seeing about 8 APs with the AR300M16-ext to over 20 with the Panda USB adapter. The problem is the only way I was able to make this work is by replacing the GL iNet firmware with the plain OpenWRT firmware.
So you used OpenWRT to be able to use the Pandas USB antenna as opposed to the standard RP-SMA antennas, is USB better or that’s just what you had around?
Would be possible to do that on another router like the MT300N Mango?
For one of my applications, I needed a long range WIFI connection. I planned on using the AR300M16-Ext, but it was not very good at picking up weak WIFI signals. For another application on my PC, I had already purchased the Panda PAU08, so I tried it on the AR300M16-Ext, and it was much better and had no problems reaching multiple distant WIFI APs, BUT the GL iNet software kept over-writing my manual LUCI configuration, so I gave up, and just went with the generic 19.07 OpenWrt software for this application. The Panda is not just an antenna but is a full WIFI radio, so you end up with two radios, one that is connecting to the remote AP, and one that is used to access the local systems, which runs faster as you are not sharing a single radio for receiving and re-transmitting.
I would not use a Mango if you ever want to use generic OpenWrt firmware, as it uses a proprietary WIFI driver supplied by GL iNet, but not available in the generic OpenWrt firmware.