One common question I get is "why do I need a firewall?" Although the default router and default firewall on your computers provide some security, it cannot protect against some more sophisticated techniques that are becoming increasingly common.
The default router firewall does one thing: block ports. It allows or disallows services from being exposed over the internet. However, this cannot protect against attacks from unsecured devices, such as your smart TV, smart thermostat, and other Internet of Things (IoT) devices. Murillo solves this by segmenting your devices into multiple categories and adding specific rules for those smart devices to prevent hacking. According to the FBI, "Unsecured devices can allow hackers a path into your router, giving the bad guy access to everything else on your home network that you thought was secure. Are private pictures and passwords safely stored on your computer? Don’t be so sure."
Along with segmenting your IoT devices from your main network, you can also separate your guests' devices from your own with a dedicated guest network. Although this functionality exists (guest WiFi), it usually doesn't support separating the devices apart from two different WiFi networks into two different subnets. It does not support segmenting into VLANs (which are more secure because it happens at the hardware level).
According to the Cybersecurity and Infrastructure Security Agency, it is recommended to have a firewall in the house. The Department of Homeland Security (parent organization of the Cybersecurity and Infrastructure Security Agency) states, "Install a firewall at the boundary of your home network to defend against external threats. A firewall can block malicious traffic from entering your home network and alert you to potentially dangerous activity. When properly configured, it can also serve as a barrier for internal threats, preventing unwanted or malicious software from reaching out to the internet."