To update your standalone lab box to the latest ESXi version, first enable SSH. Then put all the VM’s into maintenance mode and log in via SSH. Use the esxcli command to update to the latest version (mind the build numbers) by using your internet connection. So no hassle with packages, downloads, etc.

Open the firewall if needed:

esxcli network firewall ruleset set -e true -r httpClient

Update the box (this will take 5-10 minutes if using slow USB stick as storage)

esxcli software profile update -p ESXi-6.5.0-4564106-standard -d

Reboot the box, get coffee and login afterwards. You’re box is updated to latest-and-greatest. Don’t forget to update VMware Tools on the guests if needed.