Please try the following settings in the SystemSuite firewall:

1.SystemSuite > Firewall > Settings > General >Advanced Rules-> Add
2. configure as below:

GENERAL
-Rule Description: Allow ICMP Type 3,4
-Action: Allow this traffic
-Network Interfaces: All network interface cards
-Screensaver Mode: Both on and off
-Record this traffic in "Packet Log": uncheck

HOSTS
-Remote Host: All addresses

PORTS AND PROTOCOLS
-Protocol: ICMP
-ICMP type(s): Destination Unreachable - 3, Source Quench - 4
-Traffic Direction: Both

SCHEDULING
-Enable Scheduling: Uncheck

APPLICATIONS
-[not needed]

3. Ok these settings, then reboot and try your internet connection again.