how about playing the ' split tunneling" option?
Split Tunneling Select to enable split tunneling. When enabled, only traffic that requires the
SSL VPN is sent through the tunnel. Other traffic follows the user’s regular
routing.
When split tunneling is disabled, all of the user’s traffic with other networks
passes through the tunnel. This does not affect traffic between the user’s
computer and hosts on the local network.
For enhanced security, some administrators prefer to force all traffic through
the SSL VPN tunnel, including traffic between the user and the user’s local
network. To do this, use the CLI tunnel mode settings to enable
exclusive-routing.
----->taken from fortinet admin guide