The SOHO office design is intended for small, single-space offices with 1-5 computers in close proximity. Typically, this will be an office in a single space or an office set up out of your home.
In most cases, there is no need for a network switch as most SOHO firewalls/routers will have about 5-8 ports for your LAN as well as wifi. The SOHO office may also be an extension of a larger network connected via VPN.
In this configuration, there may or may not be a server on site and usually will run DHCP from the SOHO router. DNS will connect to a corporate DNS server or public DNS.
As we see in our example above, the SOHO firewall separates our network from the internet. We would arrange the DHCP pool to distribute from a range that would give us a block of unpublished IPs so we may statically assign them to network devices. Our firewall gets the first static IP of 192.168.1.1 and we set our printer to 192.168.1.2. Our PCs receive IPs starting with 192.168.1.10 so we still have 192.168.1.3-9 available for future network devices we may add at a later time.
With a SOHO network, it is not necessary to have a full 24 bit subnet as this provides us with 254 usable IP addresses. This is overkill for a network of 5-8 PCs with 2-4 network devices at most. We could reduce the amount of IPs by using a 28 bit subnet mask to leave us with 14 usable addresses instead or 27 bit if you’d like to leave room to grow.
Why would we need to reduce our number of IPs?
If this is your personal home network, there is little advantage to making this more complex. A corporate network, however, would benefit by using a 24 bit subnet block broken into 28 bit subnets for your remote SOHO sites to prevent waste of IP resources.