Netti is internet connection, but not necessarily Wi-Fi.
Yes! I reported this in a different sentence earlier, do keep reporting it...
There's a real word order issue in Duolingo.
I just now read this as "world order issue" X-D
I guess whatever the previous poster meant, a word order issue is preferable to that...
I think it's about where taas goes in the sentence. I assume "Netti on tosi hidas taas" would also be correct, although maybe with a slightly different emphasis or connotation.