Random disconnections can happen to anyone at any given time. Because it is impossible to discern someone who is disconnected by accident versus someone who disconnected deliberately, Blizzard does not reverse any leaver penalties for when you disconnect. Learn more here:
I checked the technical support forum and there appears to be no trending issues to suggest a widespread problem. So it is very likely you may have just had a one-time incident. The best thing to do in this case is play several games of quick play to make sure that you’re not continuing to disconnect. Once you feel confident that your connection is no longer dropping then continue to play competitive and you should be able earn back to your regular skill rating.