Looking for Tips on Setting Up a Tunnel with Starlink and Fortinet

October 27, 2025 9 answers
Asked by TechNinja42
I'm trying to set up a tunnel between sites that use Starlink and Fortinet firewalls. We have a hub-and-spoke setup already in place with other secondary sites connected to the hub firewall, but adding Starlink sites has proven challenging due to the CGNAT configuration. Business Starlink isn't an option for us. I've been considering the possibility of spinning up a VPS server to help facilitate the connection. I'm looking for any advice or ideas on making this work!

Answers

SecureNet99
You could also look into using an Aggressive mode IPSec tunnel; it might help with the connectivity issues youโ€™re facing.
Reply to this answer
TechNinja42
Reply to this answer
Demystifier
Have you thought about Tailscale? It's an interesting option that might suit your needs for a simpler setup with Starlink.
Reply to this answer
IPv6Advocate
While I'm currently having some IPv6 issues with Fortinet, you might be able to set up a connection using native IPv6. I've had success with similar setups on opnsense using WireGuard and IPsec to navigate around CGNAT endpoints, like with T-Mobile.
Reply to this answer
RouterBuff
Have you considered using an edge router in front of your Fortinet? It might simplify things while still allowing you to run IPv4 over IPv6.
Reply to this answer
RemoteSitePro
From my experience, using a dynamic (dial-up) VPN works well, but site-to-site won't. We also have setups behind Starlink at some customer locations, and it runs similarly to Tailscale.
Reply to this answer
FortiExpert77
To make this work, the hub site ideally needs a static public IP on the firewall. Alternatively, you can use dynamic with DDNS, but be cautious. Each tunnel from the hub to the remote sites needs a unique definition, and configure the remote sites as 'dialup' for the IPsec tunnels.

VPNWhisperer: Right, and if you have multiple tunnels, don't forget to apply an identifier for each tunnel on both ends. It can get tricky!

Reply to this answer
StarlinkUser1
Yes, it's definitely possible! You can request a static CGNAT IP from Starlink. I've managed to set this up successfully using a public address.
Reply to this answer
NetworkGuru99
I looked into this a while back and ultimately decided it wasn't feasible. I kept Starlink as a secondary internet option only because CGNAT doesn't support IPSEC tunnels, which is a major limitation.
Reply to this answer

Add your answer

Answers are reviewed before publication.

Related Discussions