How do I add my computer to my router but not the internet

[reginaldvw]

Small question. Hope this is the right forum.

I have a modem from my ISP with 4 LAN ports and they are all used:
- 2 computers
- 1 NAS
- 1 printer

I was just wondering if I wanted to add another computer do I have to buy an additional switch or is there another way? The additional would not necessarily have to connect to the internet but it would have to connect to the NAS, if possible.

 

[microchip]

a simple, unmanaged switch connected to one of the LAN ports of your router-modem combo will do fine

 

[Nullity]

You could use a firewall rule at the router to block all outgoing traffic originating from that IP, if your router is capable of such a thing.

 

[System Error Message]

Your topic is confusing with your post.
To add a PC without it connecting to internet but to share resoruces:
i dont recommend using firewall blocking, i suggest using the proper method which is to create a new vlan/subnet which the router will also be part of, the router can forward between subnets but dont forward/NAT the 2nd network so there are no firewall rules, only routes to configure.

If you use static IP for that network than you do not need the router to be part of it, only the clients whos resources are shared will need an active vlan with static IP config (or another ethernet port to passive vlan with static IP).

To add a switch just plug it into the router and plug your stuff behind it. Switches themselves dont connect to the internet like anything else except maybe for firmware updates.

 

[Zhiki4]

Hi, the post above are correct. Best will be configuring the router. For the switch port extension use i.e desktop small port like Cisco SF or SG95D.

 

[sfx2000]

Can always configure as a Link-Local address (IPv4 is the 169.254.0.0/16, IPv6 is FE80::/10) - this will allow connectivity within the local network segment - a device configured as such won't be able to jump out to the other segments (such as the internet)