You’re mixing and matching and need a little correcting. 

1. If you put the G54 in bridge (modem only) mode. You will only be able to connect 1 device. That is from the isp. Reason why is in modem only mode, nothing it controlling dhcp, nat. That is the router’s job but you disabled it. So you’ll only be able to connect 1 device to it if you’re using that mode. 
2. You can leave the router mode on and disable the wifi. That’s pretty easy to do. But why? Why not leave the wifi enabled? Whats the point of buying an expensive G54 just to disable its wifi? You’d have better off getting a modem only device then
3. Why not leave it in router mode and put the google device into access point mode (if it has that option). 
4. What I’d recommend? Go G54-→ Google Nest based router---->switch------>google nest satellites. If you need to, you can add another switch to cover all the satellites device but it should always go modem (g54) into a routers wan port then out from lan port to other switches, satellites. 

1. Understood
2. How do I disable the WIFI only?
   1. Because i purchased an “expensive” google router mesh system ($800) G54 is $700, but thats besides the point… i have a Duplex lot with two houses so to speak made of all brick walls and 100+ wifi devices. 
   2. Do you think one router can handle this? This is an honest question?
   3. Also i could not find a good modem in my area that night with an hour left before closing time, had something really important to do that night.
3. Does not have this option, i have to have one set as the primary router and the rest are set up as the points. Google seems really picky about working with others.
4. Yes, i tried this as well, problem is Google points/wifi routers only give out 1 Gig out LAN so then blocking my 2.5 switch from getting the 2.5 which then sends out only 1gig to my devices.

So you’re a little stuck. You want the usage of the 2.5gig port but the google router only has 1 gig ports and bottlenecks the system. And you bought into a google system that restricts what you can do. Are you paying for multigig speeds? Its not much point to fight for multigig speeds if you’re ISP/plan doesn’t support them. 

I wouldn’t disable the wifi. the G54 wifi is faster than the google’s wifi. You can use them together, just not integrated. So you make sure they’re on different channels and using a different SSID (name) to prevent interference. then you can self load balance a little since you have 100+ wifi devices. Meaning have the devices that are closer to the G54 and mainly stationary, connected to it for faster speeds/thoroughput. 

You can go G54--->2.5gig switch---->google router------>google access points

                                           |

                                           |

                                          V

                                Other devices (just not the satellites/access points)

Then you can still hardwired devices to the 2.5gig switch. 

Again, you’re a little stuck. You’ve bought devices that neither have the capabilities you want but you want to make them work as if they did. You’re going to have to compromise somewhere or return one of them to get the setup you want. If you return the G54, you’re google is still going to be limited to only gigabit speeds as that’s all the google has. If you return the google system, you still need to buy a mesh system that is actually multigig. And they’re more than $800 for a mesh/multigig system. the cheaper multigig mesh systems (like tp-links xe200) are still $700 for a 2 pack much less buying a 3rd satellite. For netgear, to get satellites with multigig, you have to go to the RBKE963 which is $1200 on amazon right now. Or you can go with a system where just the router is multigig and not the satellites. Those are a bit cheaper but still expensive. And you’re still bottlenecked by the backhaul.