I think there is no way to backup Deco's config, neither via the app nor via the web console. I don't see any menu item regarding backups... sorry. But, maybe, people at Tplink can give you a better...

@OeKintaro do a hard reset of the router. After the reset my router gave no problems at all except one: with Qos enabled the cpu is stuck to 100% and the device starts warming. I hope this can help...

@OeKintaro In my case the beta 1.2.0 update solved all problems. Before the update the router freezed with red light every now and then.