Can GUP Upgrade my Clients

Hi All,

I am Using SEPM 12.1 RU2 and clients of same version.

There are multiple number of GUP's in my network

Query:-

If i'll Upgrade My GUP Systems to the latest RU3, will all my clients that are taking Update from my GUP will Upgrade Automatically?

(Note:- am not going to Upgrade my SEP Manager)

What will happen if my SEPM is lower version as compared to GUP System after Upgrading them to RU3, will it be able to update all Definations and Patches required by RU3?