“I don't know... it just cuts out sporadically.”
A friend is staying with you at your apartment. He's trying to use the Internet, but it's stopped working. He asks you why. This problem happens a lot for you, but you don't know why it happens.
I don't know... it just cuts out sporadically.
When something stops working for a short period of time, it "cuts out":
Sorry, what did you say? My phone cut out.
Things that can "cut out" are services which are usually continuous, like electricity service, a telephone connection, Internet service, etc.
One of the many ways to use the word "just" is to talk about something that happens suddenly:
He was there, and then he just vanished.
It just stopped working all of a sudden.
If something happens "sporadically", it happens sometimes in unpredictable patterns.
Some examples of "sporadic" events include:
a sick person's coughing
big changes in the stock market
The word "sporadically" sounds a little bit technical. You use it like this:
The water in the building goes out sporadically. It's so annoying.