How to stop node injecting default route into LAN?

Since upgrading to 4.26.7, the node serving the LAN I have a laptop connected to has started handing out a default route via itself. I used to disable this by disabling the "WAN". How do I stop this in 4.X? I only want it to give clients a route to 10.0.0.0/8 like before. I have "LAN defult route" disable but it doesn't seem to have any effect.