I connected my iPhone/iPad with the DDJ-WeGO4/DDJ-WeGO3 but cannot control WeDJ.

Turn off the power of the DDJ-WeGO4/DDJ-WeGO3 and the iPhone/iPad without disconnecting them. Follow the instructions below.
1) Turn on the power of the iPhone/iPad.
2) Turn on the power of the DDJ-WeGO4/DDJ-WeGO3.
3) Launch WeDJ for iPhone/iPad.
If WeDJ does not recognize the DDJ even after the above procedures, please contact our support site.
https://rekordbox.com/en/support/inquiry.php