2.5 GBps Switch

If you have a modem only device and an unmanaged 2.5gig switch, you can't go modem---->switch--->router/devices. 

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                                                                                                                                                   Computer

spectrum only supplies I public ip address. And then its up to the router to take the public ip address and give devices private IP addresses (simplified version). 

The router does that. If you put a switch/device before the router, that computer will get the public ip address and will be the only device with ethernet. 

So it limits your options. 

either: 

1. upgrade to a router that has the capability of more than 1 greater than 1 gig ports. Many of netgears only have the 1x 2.5/5/10gig ports. 

2. be satisfied with the 1 gig speeds since only your PC supports faster speeds. 

3. Upgrade the modem to something like the CAX80 that has a multigig modem built in and a multigig port output. Then you could connect your switch to the multigig port and the orbi (in access point mode) to either the switch or the CAX to provide additional coverage. Not sure if the CAX is compatible with spectrum, just using it for an example.