How do I keep my secondary NVMe drive mounted after reboot?

Check the filesystem UUID with lsblk -f and use that rather than a device name such as /dev/nvme1n1p1. Device names can change between boots. Make sure the UUID belongs to the partition containing the filesystem, not a different partition.

For an ext4 filesystem, an entry would look like UUID=your-uuid /mnt/games ext4 defaults,nofail 0 2. Create /mnt/games first, and replace the UUID and path with your actual values. Use the filesystem type shown by lsblk, since ext4 would be wrong if the drive is currently formatted as exFAT.

Back up /etc/fstab before editing it. After saving, run sudo mount -a and check for errors, then use findmnt /mnt/games to confirm what is mounted there. The nofail option helps prevent an unavailable secondary drive from stopping boot.

Since the UUID entry already worked once, I would troubleshoot before changing it again. After a reboot, run lsblk -f to see whether the partition and its filesystem are detected, then check findmnt /mnt/games and journalctl -b for mount errors.

The error matters here. A missing device, a wrong filesystem type, and a filesystem that needs checking can all look like a drive that simply failed to mount. Keep a copy of the exact fstab line and the error message if you need more help.

Also worth separating detection from automatic mounting. A desktop may show a secondary drive in the file manager without mounting it at startup. If another installation detects the drive, check whether it is actually mounted after reboot and where, rather than assuming both setups behave the same way.