hi MY SUGGESTION IS GO WITH FORTIGTE FIREWALL, LICENSE WITH WITH BUNDLE AND AS PER THE USERS 100E IS MORTHAN ENOUGH , IT SUPPORTS 120 CONSURRENT USERS IN RELIABLE, GIVES BETTER SECURITY AND FASTEST TRAFFIC FLOW

Fortinet is a very good device in SMB market.. handling is very easy . very nice user interface. Comparing with all other UTMs its performance is very good. VDOM,Transparent mode,Routing,Switching like many options available.

Can you please specify the model?

For 30 employees your box is more than enough. No need to upgrade the Unit. If you are facing trouble, give me a remote session and I can try to solve your problem.