How would I have a Dell PC 2748 have ports 1-12 behave as on switch and then ports 13-48 act as another?

I assume Vlan but it doesn't work when I setup tagging.

Any help would be great thanks.

Hi,

You would create two VLANs and assign the ports that you want into each VLAN. Page 50 http://downloads.dell.com/Manuals/all-products/esuprt_ser_stor_net/esuprt_powerconnect/powerconnect-2748_User%27s%20Guide_en-us.pdf

When I assign the two sections of ports to two vlans, via the Vlan Management Tab I have it set up as follows.  

This is VLAN 2

this is Vlan 3

The VLAN 2 isn't Receiving DHCP From the Router segment, even though when i plug the second router cable into a laptop it works immediate.

Is the router sending tagged or untagged packets? It probably needs to be set to untagged, most client systems only do untagged by default.