now today it is 74.139.47.189

If you connect to the S33 directly from your PC and navigate to 192.168.100.1, what happens? What are you using as your primary router? The S33 is a DOCSIS 3.1 cable modem. It looks to me like the Unify USW Lite 8 is actually a POE unmanaged switch. You need a router to handle DHCP, etc.

My work computer shows no internet when connected directly but Teams and Outlook work. But since it is a government computer I can’t access anything. My Mac doesn’t recognize anything when connected directly. I had to grab an old Samsung netbook that my daughter had to actually log into the modem. 
 

So adding a router will fix the issue.  I was staying away from the all in one devices I had in the past. After doing some research I found that I was using Starlink and the Ethernet port on their system is actually a router. 

After you plug a computer in, you may need to reboot the modem to properly establish the internet connection. That approach should work with most computers, but it will be a “one at a time” approach. A good basic router will help, and then everything internal to your network will typically have an IP Address of 192.168.0.1 This will also make it easier to share a printer, though you may need to use a static IP for a printer to make it easily accessible.