Need help with new switch and Fortigate 80c router setup

[ccices]

I have a Fortigate 80c router that used to be connected to a layer 3 switch (3Com) but that switch died and was replaced with a Cisco 200 series switch.
My router has the default interface and a VLAN interface (Vlan ID 100)
I can't seem to configure my switch to allow my vlan to access the internet.
On the switch, I have port 1 and 2 in my VLAN
port 24 of the switch goes to the router.
The switch has ports 1,2 and 24 as untagged members, and all other ports marked as forbidden.
the default vlan 1 has ports 1 and 2 marked as forbidden.
I understand that the previous switch was a layer 3 switch and the new one is layer 2 so I take it I have to use my router to have the vlans work?
Could really use some help here!
Thanks

ideally, i would like to have 3 Vlans in total vlan 100 Lab, vlan 200 general, vlan 300 management (for access to router, switches and AP. Currently, the router, switch and AP are all on the default vlan and are working fine.

 

[htismaqe]

If the new switch is only Layer 2, you'd have to tag all the VLANs on port 24 to get them out to the router. Lookup "router on a stick".

 

[ccices]

ok.. the router is in port 24 of the switch
Belonging to VLAN 100 are ports 1,2 and 24. I leave 1,2 untagged and tag port 24
Belonging to VLAN 1 (default) I have all the ports except 1 and 2 wich are marked forbidden. I then tag port 24?
Is this the correct understanding from your comment above?

 

[htismaqe]

You'd then need to configure those VLANs on your router and setup layer 3 configs for each VLAN to allow inter-VLAN routing.

 

[ccices]

ok.. this was set up originally and worked fine. Not sure why it is not working now.
On vlan 100 I can see a PC that is on vlan 1 (the default for the switch)
From that PC, I can not see any of the pc's on vlan 100.
The configuration for the router are set up as shown in the fortigate vlan configuration.
Interface is set up, firewall is added and policy is added and still no go..
I must be missing something!

 

[coxhaus]

Going to a layer2 switch instead of a layer3 switch will only transfer the routing stuff to the router instead of the layer3 switch. I think the difference you are seeing is you need to feed the router with a trunk port on both the switch and router instead of an access port because your layer3 switch is no longer handling the routing so you are now passing the non-routed traffic to the router. Your VLANs will need tags for the trunk port. You will also need to setup the router with the same VLANs as used on the layer3 switch since the router is now handling the layer3 stuff from the old layer3 switch.
Also you will need to use the router now as the default gateway instead of the old layer3 switch so change your DHCP server setting.

 

[ccices]

okay.. still not sure where my problem lies. If I look at my router settings, I have 2 VLANS identified under an interface. The interface allows connections to the WAN. When the router is connected to the switch, any device plugged into the switch on the default interface gets internet connection.
Looking at your post above, I think the problem lies in the fact that the interface going to the WAN is not a VLAN? is that the issue?
Here is an album on imgur showing the current settings of router and switch. The router is plugged into port 13 of the router not port 24 as mentioned in previous posts. Port 1 and 2 of the switch are part of VLAN 100.
http://imgur.com/a/51byJ