Good work, nice that you have the user choice screen - auto-select for a firmware is just not trustworthy.
Until someone discovers a way of doing it natively on the 3DS this app is the best option - essentially it's a user-friendly version of the php-server method posted earlier - bur that required quite a bit of fiddly settings - this is really simple to use.
Those that don't have an android device should read the earlier thread, lots of native http hosting methods on a pc posted there.
http://gbatemp.net/threads/attempt-running-gw3-0-web-exploit-on-a-local-network.378058/unread
Yeah i think that's why Ivan went with the "YOU PICK" option rather than auto select, seeing as the auto select seems to be more buggy than user select option. garaopa said the auto select could be what's causing issues for some people as well.
And yeah there plenty of options to host it yourself at home or whatever if you don't have an android (WHICH YOU SHOULD ) haha
Might even be ways to do it on apple stuff, i wouldn't know though as i don't own a single piece of apple equipment...