You can't install kmod upgrades. there is strict version checksumming, which prevents kmod upgrades in snapshots. The kmods need to be from the same build run as the kernel itself (which you can only upgrade with a sysupgrade)
You may somewhat safely try to upgrade such add-on packages that you have installed into the router after flashing the router.
But trying to upgrade core system packages like base-files, ubus, procd etc. can lead into major trouble (as you have now noticed).