Unfortunately 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:
WARNING!
If you are at the 8 hour ban that means you have left multiple games already and risk getting a season ban if you continue to leave games. A season ban will disqualify your season results and lose all end-of-season rewards and you will be one step closer to a permanent ban from Competitive Play. Suspensions and bans from Competitive Play CANNOT be appealed. If you are disconnecting frequently, AVOID playing Competitive Play.
Remember if you see the message, “Lost Connection to the Server” in the title screen or the message “Failed to Connect to Server” in yellow text in the text chat box, this means there is something that disrupted your connection to the game server and not a problem with the game server itself. There can be a variety of reasons this happens including those that don’t disconnect your computer from the Internet. There is great troubleshooting to start with that can most likely resolve most issues and I encourage you to check them out here: