How to stop Windows 10 restoring unwanted default gateway route

I'm trying to disable internet use while allowing the LAN (via a Wi-Fi router) to keep working, as is described here and here . When I use route delete /p 0.0.0.0 mask 0.0.0.0 to remove the default gateway and then create another default gateway entry that points to a nonexistent address instead of the actual gateway, this successfully removes the correct default route for a short while but something then restores it. Using the /p switch for persistence doesn't make any difference. If I use route add /p 0.0.0.0 mask 128.0.0.0 and route add /p 128.0.0.0 mask 128.0.0.0 to add dummy routes with a

Question by velw on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.