by Ken Task.
DB imported has retained URL's to original server ... production server.
Did you search and replace in standby server the URL's contained in the standby DB?
Search for 'production server URL' ... replace with 'standby server URL'.
Did you edit config.php flie of standby server to reflect new hostname/url?
https://docs.moodle.org/29/en/Moodle_migration
'spirit of sharing', Ken