In one embodiment, a parent node in a directed acyclic graph (DAG) in a computer network may detect congestion from its child nodes. In response, the parent node may determine particular child nodes to expel from the parent node based on the congestion, and notifies the expelled child nodes that they must detach from the parent node in response to dynamically detecting congestion (e.g., to find a new parent, excluding the parent node and optionally any nodes in the vicinity). In another embodiment, a child node receives a detach request packet from a current parent node that indicates that the child node is expelled from using the current parent node. In response, the child node triggers a new parent selection to select a new parent node that specifically excludes the current parent node (e.g., and optionally any nodes in the parent's vicinity).