Hello samppa10s, thanks for posting and sorry to hear about your ban for disconnecting from a ranked match.
Usually if you were affected by a DDOS attack, you would start rubber banding across the screen whilst your ping counter rapidly jumped up and down, you would then be disconnected.
As you experienced the 2-0x0000C015 error code in particular, would you please try the following troubleshooting steps according to your console to see if it prevents this disconnection from the server from happening again? -
PS4 -
https://ubi.li/12soI
PS5 -
https://ubi.li/JE6K7
Xbox One -
https://ubi.li/6L9Js
XBSX/S -
https://ubi.li/55G8e
In case this was caused by any degradation that has affected a few players, please make sure to check these websites also, should this error code pop up again -
Siege server status -
https://rainbow6.ubisoft.com/status/
PlayStation server status -
https://status.playstation.com/en-GB/
Xbox server status -
https://support.xbox.com/xbox-live-status?xr=shellnav