Troubleshooting Tip: Packet loss with Starlink GEN2 as WAN router connected in any FortiGate interface

If Starlink is directly connected to any WAN1/WAN2/DMZ/any internal FortiGate ethernet interface using the Starlink ethernet adapter, packet loss may be observed.

To configure Starlink with FortiGate, refer to Technical Tip: Deploy the Starlink router as WAN for the FortiGate with the default LAN subnet (192.168.1.0/24).

The packet loss issue has been reported frequently and has been investigated internally by our R&D team and it was determined that there is a Physical compatibility issue in Starlink GEN2 adaptors.

This issue is reported by other vendors as well.

There are two workarounds found and used so far:

1. Use 100M speed instead of 1G. This can be done by editing the WAN interface in the CLI:
   
    
2. Add a switch device between FortiGate and Starlink adapter. Even a 'dumb' non-managed switch will work.

Note: Not all switches may work. Try different ones.

This issue has been reported by multiple users and vendors:

• https://www.reddit.com/r/Starlink_Support/comments/vypze3/starlink_gen2_compatibility_issue_with_3rd_party/
• https://forum.peplink.com/t/throughput-issues-when-connecting-to-a-starlink-gen-2-router/41293
• https://community.tp-link.com/en/home/forum/topic/563220

To troubleshoot packet loss on a FortiGate device,consult the following articles:

• Troubleshooting Tip: First steps to troubleshoot connectivity problems to or through a FortiGate with sniffer, debug flow, session list, routing table
• Troubleshooting Tip: Diagnose Packet Loss