Install a device in between the router and modem to restrict access to inappropriate sites.
Install a device in between the router and modem to restrict access to inappropriate sites.
If you can’t manage the host PC… any fix you try won’t work. In short, pihole would help (no soldering required… why keep emphasizing this? You just need a USB to Ethernet adapter to turn a Pi into a router, but you’re not even using that, you only need one Ethernet port which a Pi provides) though you’re right about DHCP’s DNS—it can be easily bypassed from the PC. The only real way to block access is by controlling the machine as admin and changing settings like DNS. This would let you set up pihole properly and prevent changes. Or it could let you install software that can’t be removed, using group policy tools. I mean “stuff” because I haven’t done it before… but it’s probably the only option. If you’re trying to hide it, it won’t work if they stay in admin mode. If you keep their permissions, it won’t either.