I receive "Connection was terminated unexpectedly." when trying to connect via mobile Hotspot

[StefanC24]

Hi everybody,
when i try to connect with forticlient vpn i receive a "Connection was terminated unexpectedly."

this happens only in my personal hotspot (iphone; telekom). when i try it with a hotspot of my colleague (also iphone; telekom) it works. it also works within our companies wifi.

we are not connected to any VPN with our iPhones. apple private relay is also disabled

could any other iPhone setting cause that problem?

[adambomb1219]

Most likely CG-NAT getting in the way. What do the FortiGate logs say? Does the firewall even see the request? The carrier could also be blocking this. IKEv2?

[StefanC24]

Thanks for your answer.

Seems the issue is that i only get a IPv6 by my provider and cannot change it. With this the IPsec configuration is not working..