I wish to draw your attention to a problem applying 2018-01 TKU on an appliance earlier than 11.2: an upstream package naming problem leads to a failure and a non-working appliance *if* this is subsequently upgraded to 11.2.X. This is not good.
To reiterate: the 2018-01 OSU will install fine on 11.1, and you might want to do that for Meltdown/Spectre mitigations. But you should not attempt an upgrade to 11.2.X on a 11.1.X / 2018-01 OSU appliance. I expect we will issue a new OSU you will need to install on 11.1.X before upgrading to 11.2.X in this situation. [UPDATE: New OSU 6.18.01.30_727098 is now available on EPD and replaces the previous one]
It would be fine to take an 11.X appliance on a pre-2018-01 OSU, upgrade to 11.2.X and apply 2018-01 OSU to it.
While OSUs are normally very easy to apply (UI upload; wait a bit; reboot) this reminds us that no change is completely without risk, and updates should always be applied on UAT first - before considering a production upgrade.
For reference, this is tracked as defect DRUD1-22350.