What must I do to fix this?
Install the latest snapshot, or the RC6.
and how do I do this
Edit: Missed some detail I got it now
Snapshots go out of date and then if you want to add a package (especially a kmod) you have to start over by upgrading the whole OS. Thus the release or RC build is preferred for general usage.
Do an upgrade, like any other release.
Since you don't have the webui, run sysupgrade from ssh after you've DLed the sysupgrade image to the routers /tmp folder.