I have a client's firmware OS which has not been updated for years.
They are on version 11.11.4 (build 514824). Can I upgrade them straight to latest OS version 12.5? Or Do i have to do all the incremental versions one by one?
The Release Notes will tell you if there are any needed intermediate upgrade steps needed.
There have been a few important changes since your release:
. SD-WAN applies if you have a multi-WAN setup, especially if you are currently using Policy Based Routing, which is replaced by SD-WAN
. DNSWatch is a new subscription service
. Bitdefender replaces AVG antivirus
. new IMAP proxy
. new Access Portal for larger firewall models
Make sure that V12.5 can be installed on your firewall model.
Also you need an active LiveSecurity license on your firewall to do any firmware upgrade.