Really I don't think this is new to v17... I have a couple different clients with Fortigate firewalls. I am using SFOS XG 17 RC1 at home with an IPSEC connection to some of them. I have had an ongoing problem where when for whatever reason the connection drops I can't get it back up. Resetting the firewall doesn't help. But a firmware update on the SFOS always brings it back up.
I get the following in the logs.
IKE_SA timed out before it could be established
Since a firmware update fixes the issue I think it must be the SFOS that is the problem.
Does anybody have any ideas?