WIFI privacy warnings-an ultimate removal fix needed

I have been following the various responses to Community questions re removing the Privacy warning notification that is immovable. The warning appears on my iPhone xr and all other devices that use my network--but the warning just won't shift.

I am using a new router with one new TP extender-both connect well and there are no operational issues.

Can somebody advise me in very simple terms how i can remove these warnings-forever.

Many thanks