communicate two branches that are behind a cgnat

[Igneus]

Hello, I have 2 branches that have 3 links each (this due to the instability of the ISPs). In both branches I have the same 3 ISPs. 2 of these ISPs do not offer a public IP, but rather an IP from their LAN (CGNAT), I want to connect these branches via VPN through these ISPs, I talked to the carriers and there is no way they forward a port to my branches. I read in a similar question that this can be solved using a hub-to-spoke VPN, placing the hub in some cloud or site with a fixed IP and making my 2 branches spokes. is there a tutorial on how to do this? 
the services i want to comunicate are: 
voice, BD´s, and web internal servers

[hbac]

Hi @Igneus,

Hub and spoke is referred as ADVPN. You can refer to https://docs.fortinet.com/document/fortigate/7.4.3/administration-guide/820072/advpn-with-bgp-as-the...

There should be a way to do port forwarding on the ISP side to forward traffic to FortiGate IP address. Even a home based ISP modem is able to do that. 

Regards, 

[Igneus]

Hi @hbac 

Thanks for the answer, the problem with the ISP is that the nat is on my modem and in the router of my carrier something like forti WAN GW is: 192.168.100.1 the modem of my isp GW is 169.100.201.x dinamically assigned. and if i ussed whats my public ip theres another ip. CGNAT

[Broodkast]

Maybe use IPv6 to set up the tunnels.

https://docs.fortinet.com/document/fortigate/7.4.4/administration-guide/600821/ipv6-ipsec-vpn

https://community.fortinet.com/t5/FortiGate/Technical-Tip-IPv6-ADVPN-Hub-and-Spoke-Deployment/ta-p/2...