IIRC all the backbone of glastonbury is put in place in about the week before it.,.
It's one of, if not the biggest and most complex outside broadcasts in the world* that is done from scratch, and these days they have a fraction of the staff on site providing more coverage than they did 20 years ago. It's incredibly complicated, and a lot of the time things that can go wrong to stop the broadcasts can be simple hardware failure that can happen any time, or are fixed within minutes.
Depending on the actual fault it might be up on iplayer later.
*Unlike the olypics etc they have to put everything into place specifically for it, including the most "basic" stuff like power. IIRC these days it usually involves sound and vision from a dozen or more stages with dozens of feeds.