Omniswitch with firewall

[madrid272001]

Hi everybody,

Hope you can give me a hand.

I will explain my problem. I am going to install a firewall (fortigate 90D). My configuration is as follows: I have got an adsl router. From one port of this router I have a cable that goes to the firewall and from the firewall, another cable to the onmiswitch OS6450.

With this configuration, I get no internet. But nevertheless, if I get rid of the onmiswitch (I mean, I connect my adsl router to the firewall, and from firewall to one computer), it works perfectly.

Do I have to change something on the omniswitch????.

Thanks for your replies.