I haven't looked at v.14 of the firmware but it reminds me to mention that I emailed ZyXel with a couple of firmware requests some time ago.
The first was to do with re-enabling multiple telnet sessions to make it easier to use line monitoring software.They refused citing 'security issues'.
When asked what this meant:
The issue caused by multiple telnet sessions is that there is no real control over who is telnetting into the device. By limiting this to one, there has to be a dedicated telnet login by the admin who wants to alter the configuration.
Instead, they provided me with a CLI command list for the modem (attached) but unhelpfully went on to say 'but we can not verify that this contains a command for the desired function'
The second request was to raise the maximum MTU setting from 1492 to accommodate the use of baby jumbo frames which BT/Openreach support on their FTTC equipment.
In response to this I was told
We will kindly inform you that for the moment this is not possible. Your feature request has been forwarded to our product management.
Might be worth others contacting ZyXel to request these changes if you want them as well - via support@zyxel.eu