There used to be a feature called 'Port-Based VLAN' that was really handy in hotels or shared environments where you shared Internet but don't want any connected devices talking to each other via that switch. This feature is hard to find on modern switches as they mostely support 802.1q VLANs and if deployed using 802.1q would otherwise require an IP subnet per port which is a lot of work and complexity. 

There is a solution that can be used on most NETGEAR managed switches called 'Protected Port'. It's not exactly the same as Port-based VLAN but does essentially the same thing for a single uplink situation & is very easy to deploy. In my screenshot below I have made an example using port protection. In step 4 I selected all ports then de-selected my uplink port to connect to the router. Now all ports are private from each other but have upstream access to Internet. Mix and match protected/unprotected ports as required.

Example on a GS748T(v5) with copper port #1 as uplink: