Public IP's assignment - DHCP problem within VLAN

[Mikron1982]

Hi everyone

I'm facing a problem i cannot solve with a SG300-20. Hope someone have a hint.

What i try to do is, to create a VLAN for allocating Public IP's from the ISP.

The infrastructure is as followed. Got a cable modem with one ethernet port from the provider. That is connected to the SG300 port 1.

Then i got a firewall with two ethernet WAN ports. Those are connected to the SG300 on port 2 and 3.

Port 1-3 are access ports with the VID2.

The SG300 is in layer 3 mode.

The WAN 1 of the firewall get an dyn IP but the WAN 2 not, because the ISP assigns the IPs out of different subnets.

[Mikron1982]

Someone please?

I also checked it out when i switched to layer 2 mode.

Also tried to add dhcp relay to the dhcp server of the provider.

Notihing works.