I use the latest version and it seems that sometimes it works, and sometimes it doesn't. Don't know why either. I'm also using A9LH, and tested on both Luma3DS and Corbenik and both just randomly work and don't work.
You shouldn't have to use firmware.bin with the latest BootNTR as it adds support for 11.0 FIRM. But in my testing that should help that problem if it does occur, so I'm unsure what your issue actually is.
Same thing happens to me - It seems to not work after opening anything on your 3DS/a game turns off/resets wifi
Its really weird.
Turn off your 3ds and turn it back on - Dont open it straight away or it wont work wait around 10 seconds after being on the home menu then open it up.
Its really odd