I have installed A9LH, and LumaCFW on 11.3 on my New 3DS XL US model, and this message started to show up randomly. Every time I tried to turn it back on it showed this message like 5 - 60 seconds after being turned on. I tried turning off clock speed + L2, removing A9LH entirely and system reset, updating to 11.3 (this error started when I was on 11.2), and re-installing A9LH and CFW over again. I read online that it has to do something with a WiFi card? inside the 3DS but I'm not entirely sure. The message went away for a short while and I was able to play, but after 4 days it came back, and more frequently than before.