Firewall firmware updates from v5 to v6 and will it affect FortiClient VPN user

[Charles_Chen]

I have a FortiGate firewall 100D and I want to update the firmware from version v5.0.9 to v6.0.7 to keep it up to date. I'm just wondering if I do so, will it affect my FortiClient VPN users? And if it does affect then what can I do to prevent it from affecting my VPN user?

[Toshi_Esumi]

From 5.0 to 6.0, you need to go through 5.2->5.4->5.6. It's a lot. Noboy doesn't want to, or can't, guarantee the Forticlient VPN wouldn't break. But probably FortiClient is the last thing you need to worry about. I would worry other regular firewall functions and configuration, then site-to-site IPsec VPNs if exist, admin access since required encryption level will change, and so on and on...

If FortiClient VPN(IPsec or SSL VPN) breaks, all you need to do is to save the config, uninstall the current FortiClient and re-install the lastest one (VPN only), upload the saved config. The latest should work with 6.0 with fresh install.

I would try phased upgrades, one major version at a time, and check everything is working next morning, then schedule the next upgrade. Don't forget to save the config every steps of upgrade so that if you found something was broken and you determined you can't fix the problems in reasonable time frame all users can bear, you have to flush the boot drive and load the original image, then upload the saved config to go back.

By the way, I don't recommend 6.0.7 mainly for the vulnerability fixes added after that version. Go to the latest 6.0.11.