I wasn't getting d/c at all but noticed others around me with the d/c symbol, then people disappearing as they dropped. People would complain in chat but it didn't start affecting me until today. It's been pretty frequent. When OP says it's unplayable, it can be depending on what you're doing. Short dungeons and gathering would probably be fine, questing here and there also fine. But for something as dedicated schedulewise such as raiding, I could definitely see that ending the night, especially if it is affecting more than one person on the raid team.