The last couple of times I went to Yellowstone in early- to mid-June, it was pretty cold and the crowds weren’t too bad yet. This time, not so much: it was ten degrees warmer, day and night, and already crowded. All the campgrounds weren’t even open yet, though there was no reason they couldn’t have been, weather-wise. I guess I’ll need to start going in May. Thanks, global warming.
The internet situation has improved quite a bit since my last visit a few years ago. There is now cellular data service from Verizon at Mammoth Hot Springs, Canyon Village, Old Faithful, Fishing Bridge (including the Bay Bridge and Lake areas), Grant, and of course in West Yellowstone. The signal is at its worst at Canyon Village because the cell tower isn’t in the village, but rather up the mountain to the north. It’s non-functional in the cafeteria there, which is a bummer, but saves you from the truly awful cafeteria food.
On the other hand, it may lead you to the discovery that there actually is good pizza in Montana.
There is also paid WiFi at Old Faithful Snow Lodge, Canyon Lodge, Lake Lodge, and the Mammoth Hotel. Twelve bucks a day, twenty-five for three days, and paying for one gets you access to all. (You don’t need to be staying there, and there are plenty of public areas with power outlets.) The WiFi becomes slow and unreliable at peak usage time in the evening when all the tourists are done touring, and so does cellular data.