Hey there, there have been updates to this. Blizzard Customer Support have identified the issue specifically to certain Internet Service Providers.
As a reminder, all disconnections and game crashes counts as leaving the match and will be penalized appropriately. The game server has no way to discern a legitimate disconnection or game crash from one that is forcefully caused by a dishonest player to bypass leaver penalties. You can learn about this policy here:
EDIT/UPDATE: Blizzard made a follow up post, it sounds like they are working with the ISPs to reroute players affected off the affected backbone hub: