Help: Site-to-site IPSec VPN drops every 24 hours like clockwork.

Hiroyuki · 2026-08-08T11:55:48Z

Hi everyone, new to FortiGate and this community. I’ve set up a site-to-site IPSec VPN between our main office (FortiGate 60F) and a remote site. It establishes fine, but the tunnel drops exactly every 24 hours. It reconnects automatically, but the interruption is disruptive. Our phase 2 lifetime is set to the default 3600 seconds. Could this 24-hour cycle be from a phase 1 setting I’m missing? Or is there a common scheduler or key refresh timer I should check? Any pointers on where to look in the config would be really appreciated. ?^?

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calebs

(@calebs)

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09/08/2026 12:08 am

Right. That 86400 default is everywhere. The problem is the other side might have it set to 28800 or something nonstandard. The tunnel will come up, but then it'll fail after *their* shorter lifetime, which can look like your 24-hour timer is the issue. You have to check the negotiated SA timers, not just your config.

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