Connect SG220 to unmanged switch and/or Fortigate firewall

[aviron2021]

Hello,

I tried to connect fortiget 60e with sg220 in a simple configuration without VLAN's  just need 20 pc to communicate with the firewall as a gateway.

The cisco is configured to its default configuration with the latest firmware all ports are set to trunk by default.

The  PC's are not able to communicate with the firewall it is the same when cascading to other unmanaged HP switches.

Please advise

[marce1000]

                              >....all ports are set to trunk by default.

  - What do you mean by that , normally the PC's should be on a port in 'access mode' and or assigned to  one-vlan (only).

 M.

[aviron2021]

All the ports are set to trunk mode by default.

I tried to change it to access mode but I received an error I can change it to general. Should it be on general mode?

I was also recommended to disable spanning tree. What do you think about it?

Thank you for your help

[marce1000]

 >....I tried to change it to access mode but I received an error I can change it to general.

                   - Which error do you get ?

M.

[aviron2021]

The error is "Port must be in general or trunk mode" 

I received the error after the command 

switchport mode access

 What do you think about general and disable STP?

[marce1000]

 - No , for PC we need access mode , can you post output of show version ?

 M.