DHCP not working after configuring vlans

So I had a fully functional network with dhcp running successfully.

I have a Cisco 1921 router and a switch. I have connected three pcs to the switch and also the dhcp server.
Now I want to put two pcs out of three onto a different vlan. But when I do that, the dhcp server is not on the same vlan anymore. So these pcs are not able to get ip addresses using dhcp anymore. If I put the switch interface connected to the server to the new vlan than other pcs will be on different vlan and the same problem will occur with those pcs. I tried putting the interface connected to the dhcp server into trunking mode but that did not help at all.

Any suggestions on fixing this are appreciated.

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Comments

atorven

Use the ip helper-address command on each sub-interface on the router pointing to DHCP server.

Deathmage

dellpe wrote: »

So I had a fully functional network with dhcp running successfully.

I have a Cisco 1921 router and a switch. I have connected three pcs to the switch and also the dhcp server.
Now I want to put two pcs out of three onto a different vlan. But when I do that, the dhcp server is not on the same vlan anymore. So these pcs are not able to get ip addresses using dhcp anymore. If I put the switch interface connected to the server to the new vlan than other pcs will be on different vlan and the same problem will occur with those pcs. I tried putting the interface connected to the dhcp server into trunking mode but that did not help at all.

Any suggestions on fixing this are appreciated.

this may be a silly question but do you have routing between the vlan's? - ie if you don't have routing, how will they know to communicate with the other?

ahaha

Agree with Deathmage, you should check the VLAN between the Cisco 1921 router. If do so, put your answer or question share with us.