Solution: I reflashed my S9+ today and the problem is resolved. Download firmware ending in H1 from Sammobile website and use ODIN to reflash to old frimware. There are links on other threads how to do this, and it was successful for me today on S9+. The recent firmware update to H7 completely killed my phones performance. I have an unlocked phone ( SM-G965U1) from the US being used in Australia, and this problem seems to be common to that phone being used outside of the US. https://www.sammobile.com/samsung/galaxy-s9-plus-us-unlocked/firmware/SM-G965U1/XAA/ Follow the instructions on right hand side of Sammobile website and it worked perfectly for me.
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