A red light on the Linksys Velop node can be dangerous which needs to be addressed quickly. That can be due to several causes but the major reason for this is no connection between the child and parent node. If the ethernet wire is not able to connect those nodes strongly there will be a Linksys Velop node blinking red for sure. To fix that, check whether the ethernet wire working first, whether that is capable of attaching the nodes together or not. If that is not, then replace the cable with a new one and try to select the latest wire.