Salvē! I am new here and searched the questions, but could not find anything. In another site somebody suggested: interrete trans spiritum, but this seems too long. Maybe a catchy abbreviation such as wifi but using the words in Latin? Any suggestions?
The name Wi-Fi never was an abbreviation of "wireless fidelity". Therefore I see two approaches to naming it in Latin:
Use Wi-Fi as a name.
Express the idea "wireless network access" somehow.
In the first approach the name would be indeclinable, so there is no case inflection. Cases can be expressed by an auxiliary word (possimne uti Wi-Fi tuo?) or the syntactic role can be clarified with prepositions (per Wi-Fi interrete adhibemus) word order or other similar structure (visne Wi-Fi?).
In the second approach there is no reason to translate the word "fidelity" in any way. The basic question is to find a good translation for "wire" or "cable". The second one seems to come from the Latin capulum. Using that, we could say rete decapulatum, "a wireless net".
Both approaches have their merits. The first one is at least very simple to use and understand, so that would be my first recommendation.
To me, wifi feels like a word that the Romans would have just borrowed rather than used their own phrase for. If you swap out the W for a V and treat it like a third declension noun, you get vifis as the genitive noun. I'm not sure how awkward that would sound to those more experienced than me, though. I suppose it's better than vaefae, though. :)