Generally, yes. WAN -> modem -> router -> switch -> (devices, wireless AP, other switches).

If you set the internet provider's device to modem/bridge mode, it will do one thing, and one thing only: forward traffic between the ISP's infrastructure (like DOCSIS, telephone line, PPPoE, FrameRelay, etc) and an Ethernet port. The traffic on that port will be unfiltered and dangerous internet traffic.

The first device after the modem should be something with a firewall and NAT. In most cases, this is a consumer-grade router, but it could also be a computer running pfSense/OPNsense/OpenWRT (which basically turns it into a router). The firewall's role should be obvious -- it filters everything that passes through it, and only allows permitted traffic.

NAT (Network Address Translation) is a bit more complex. I'll skim over the details -- it allows you to have a private network of any size communicate with a public network using only a single public IP address (which is usually supplied by the ISP). It also enhances security because NAT is what facilitates port-forwarding, and your private network won't be exposed through the public address unless you do that. NAT is almost always handled by the router. Firewalls can be integrated into the router, integrated into the modem, or implemented as a discrete device -- make sure that the internet traffic passes through at least one firewall!

The router in this case handles NAT, finding the first hop on the internet for outgoing traffic, and routing incoming traffic to the subnet that contains the destination device.

From the perspective of packet switching on the network, a wireless access point is really no different than a switch, except it facilitates communication with wireless devices. Depending on the model, APs can support VLANs, and each wireless network can be assigned to a different VLAN on the same device.

For example:

• "family" wifi network on VLAN 100 with a password for trusted devices
• "guest" wifi network on VLAN 101 with open authentication for untrusted devices
• Connect the AP to a port on the switch, set those ports to trunk mode, and allow VLANs 100 and 101
• Set the rest of the ports, where the wired devices will be connected, to access mode on VLAN 100
• Give each VLAN a different subnet (e.g. 192.168.0.0 for one, 192.168.1.0 for the other)

This way you can set up the router to allow both subnets to communicate with the internet, the family subnet to talk to devices on the guest subnet, but prevent guest devices from talking to the family subnet.

How you achieve this depends on your ISP and what devices you own. For example, the ISP might only give you an IPv6 address, which is an altogether different headache.