How can I upgrade an offline 2.2.6 pfsense?
The manual states: "When upgrading from 2.2.x to a current version, the firewall must first stop at the latest pfSense 2.3.x release before it can proceed to pfSense 2.4.x or later. ".
Where can I find a 2.3 version?
Before you do anything is your hardware 64 bit? Where you running a 64bit or 32 bit version?
What is your storage media, if its a small SSD then maybe take a image of the existing install and then wipe the SSD and install 2.4+ from scratch.
I think that would be a easier way forward and gives you a fallback plan (reverting to image taken). You would have to probably set up all your rules and settings again.
But others might have a better suggestion.
It is amd64
Is the 2.2.6 32bit or 64bit? Nano bsd versions of 2.2 were 32bit.
You really need to just clean install would be my suggestion.
There have been significant changes from 2.2.6 days, new UI, package system, there is a chance your interface names (from em to igb) will have changed.
I would do as @johnpoz suggested, first take a backup, install the latest, make sure it's up to date, on 2.4.4-p3, restore your backup.
There have been significant changes from 2.2.6 days
I nominate this for "understatement" of the week ;)
You could download an upgrade image for 2.3 if you can find one, and upgrade to that offline, but that only gets you to 2.3. There isn't a way to live upgrade from 2.3 to 2.4.x offline.
Reinstalling would be much faster and easier.