VPN IPSEC on Iphone via mobile data

Hi all

I have a strange isue. When I try to connect Fortigate as VPN from Iphone via mobile data after connection Phase 1 negotiation success not going to Phase 2, but delete Phase 1 connection.

BUT  When I try to connect Fortigate as VPN from Iphone via WIFI there is no any problem.

It was working before upgrade to version 6.04. Is there any suggestion.

Thank you

iincitr