TLS error on website when connected via vpn.

We are using Forticlient to connect to our Fortigate 100D via an ipsec VPN tunnel. When connected, all works fine except for a particular website. We get, "Can't connect securely to this page. This might be because the site uses outdated or unsafe TLS security settings".

We can put the computer on the local LAN and it connects to the site just fine.