I have an Mini-4 Tablet,  that is using IOS 13? for it. I have installed the latest Dji app.  I have the Flight Remote Controller 231. and havewatched the video on linking, but it does not link.  Any help is greatly appreciated.  Will gladly answer what questions I can.

Hello there Bob-Mini-2. I am sorry for the trouble this has caused and thank you for reaching out. Can you please try to uninstall and reinstall the DJI Fly application and try to link the DJI Mini 2 once again or try using a different recommended mobile device for us to be able to isolate the said issue. Thank you.

DJI Stephen, I will do as you say.  Also, I am going to delete GO 4 from that tablet to see if that helps.  The  apple os I have is ipad IOS 13.7.    Thank you Stephen.

DJI Stephen, I have found my problem.  I did delete Go 4, just in case, and deleted Dji Fly, re-installed it.  While looking at the Flight Controller, I noticed a white on red banner on the screen
in the screen that said the Controller was not connected to a mobile device.  I could not see how that could be, the cable was attached to the port of the controller,
(the one used for charging), and then connected to the tablet.  It should be connected.  But it kept bothering me that in  the little displays it showed the cable coming from near the back of the controller.
Well, I looked all over the back of the controller for a port and found none.  Then . . . I lifted the holder for a cell phone/pad, and did not find a port.  Then feeling around in the recess for the holder,
I found the cable, with one end in a port, and the other end in a small recess for it.  I took out the cable, connected one I had, which was longer, between
the (newly found) port and the tablet.  All is working fine.     Also I note that originally I had set-up the Mini-2 with the newest version of Dji Assistant 2, so that is to say that
apparently it was set-up correctly.  However, when it gave me the opportunity go to Dji page, I read a small window that stated that IF I went there, some things on the
device (Mini-2) could be changed, so I did NOT go there.  Also, when I did get connected to the Mini-2, the firmware was updated to Version 1.2.1, and a notice that
new features had been included, but an update to Version 1.2.2 was needed to use them.  Thank you for your help.
and all is working fine.