Thanks for posting your question in the Support Community! I think you're very close with this configuration. I don't see any problem with the 3448 config. The Netgear switch appears to have VLAN 1 untagged for all 24 ports, but VLANs 2 and 3 are also untagged for their respective ranges. I recommend using Netgear's "advanced" or 802.1Q configuration options. If I recall correctly, you need to (a) set the default VLAN membership for each port (VLAN 1 for port 1; VLAN 2 for ports 2-12; VLAN 3 for ports 13-24). And (b) setup VLAN 1 to be untagged only on the trunk port--port 1--and make it tagged for 2-24. Leave VLAN 2 untagged for 2-12, and VLAN 3 untagged for 13-24, as you have it listed.