Could a three-port Ethernet switch provide the benefits you need?
Could a three-port Ethernet switch provide the benefits you need?
This appears to be an unusual inquiry that likely should have been addressed during the early days of internet infrastructure. Normally, an Ethernet cable connects the modem to the wireless router's WAN port. The other four ports on the router can be utilized as needed. If you have extra ports available, you won't require a dedicated Ethernet switch.
You prefer a switch that uses PoE without needing a PoE injector. If that's the case, you'll still require an injector somewhere along the line to supply power. There are PoE-powered switches available, but they tend to cost more than basic switches with a standard 12V plug. The injector itself will perform similarly to a non-managed switch from Amazon in terms of price.