During start-up, I get the message, “Nvidia kermal module missing, reverting to nouveau”
Hello Jim and welcome to ask 
It seems you may have installed the nvidia drivers and that they are failing to properly load. You do not tells us any details about your system so we have to guess from the one message you posted.
If my guess is correct, and if you actually have an nvidia gpu in your machine, then it seems quite possible that your bios has secure boot enabled which can prevent loading of out-of-tree modules such as the proprietary nvidia driver.
Please post the output of dmesg | grep -iE 'secure|nvidia|nouveau' and dnf list installed '*nvidia*' using the preformatted text tags available with the </> button on the toolbar so we can see what the system is actually telling you during boot about those items.