This version is compatible with motherboard alix 2013? 256 ram.
Regards
No, the minimum is 512MB: https://wiki.opnsense.org/index.php/Hardware_setup - as I mentioned in your other thread.
I use it on an alix2d13, without any problems in operations. For obvious reasons things like suricata (IDS) and squid (proxy) do not work with 256MB of RAM.
When updating I often ran into problems, since OPNsense loads the packages to update into the /tmp RAM disk. I could successfully update the last time by disabling the RAM disk, rebooting (to actually disable the RAM disk), perform the upgrade, and (optionally) enable the RAM disk again. If you do not use the RAM disk, maybe you do not have any troubles at all...
I use the DNS forwarder, the DHCP server, IPSec VPN, and traffic shaping, without any notice of performance impact. See attached screenshot for RAM/CPU usage.
System upgrades are going to improve for nano setups.
I once ran OPNsense on an WRAP wih 128 MB RAM, but had to disable HTTPS and hack the nano image because it doesn't work in packet mode... :D