Update your single ESXi machine from the command line with the update saved to the datastore.
Upload the patch file to your datastore and check the md5sum with the vmware kb52236
[root@localhost:/vmfs/volumes/datastore1/] md5sum ESXi650-201801001.zip
1e4a80c89e0afa6249c82ea1d2105e9a ESXi650-201801001.zip
To update ESXi you need the correct profile name from the update file, list the profile names as followed:
[root@localhost:/vmfs/volumes/datastore1/] esxcli software sources profile list -d /vmfs/volumes/datastore1/ESXi650-201801001.zip
Name Vendor Acceptance Level
ESXi-6.5.0-20180104001-no-tools VMware, Inc. PartnerSupported
ESXi-6.5.0-20180104001-standard VMware, Inc. PartnerSupported
Use the correct profile name to update your ESXi machine, normally this is the standard one.
[root@localhost:/vmfs/volumes/datastore1/] esxcli software profile update -d /vmfs/volumes/datastore1/ESXi650-201801001.zip -p ESXi-6.5.0-20180104001-standard
Reboot the ESXi machine.
[root@localhost:/vmfs/volumes/datastore1/] reboot