Yes. So your ISP Gateway is combining a modem and router and typically runs software the ISP is in control of.

I prefer to take control of all aspects of my network. The Arrus modem is just a good but stupid modem that only is a modem.

The protectli vault runs firewall software that lets you decide what kind of internet traffic is even allowed on the network and can control with a fine grain different subnets and vlans.

The Flint 1800 is a highly configurable router and wifi router behind the firewall. It runs mullvad on the router level, in addition you can isolate devices even further by grouping them onto their own password protected networks.

In this way I can make it so only certain devices can connect to other devices and only certain internet traffic can reach certain networks.