Learn Spanish (Latin America): El wifi acababa de fallar durante la llamada. - The Wi-Fi had just failed during the call.

The phrase acabar de + infinitive is a special expression that means "to have just [done something]." When talking about the past ("had just"), we use the imperfect tense acababa. We don't use the preterite (acabó) or the past perfect (había acabado) for this specific meaning. So, acababa de fallar perfectly translates to "had just failed."

How would this sentence change if I wanted to say "The Wi-Fi HAS just failed"?

To say something has just happened right now, you simply use the present tense of acabar. The sentence would be: El wifi acaba de fallar. Since our original sentence happened further in the past ("had just"), we shift the verb to the imperfect: acababa de fallar.

Can I use fallar for failing a test, or is it only for technology?

Fallar is great for technology crashing, systems malfunctioning, or someone making an error. However, if you want to talk about failing a school test or a class, you would use a different verb, like reprobar (very common in Latin America) or suspender.

Is wifi always masculine in Spanish?