As suggested, you need to look at in your alert log file.
Also, you can check v$archive_dest_status, specifically the STATUS and ERROR column, that will tell you what error is being reported when primary tries to send the archive log to the standby.
Both of prod and DR listeners are up and running ?
Can you please pate result : (in Primary database)
SELECT status, error
WHERE STATUS <> 'DEFERRED' AND STATUS <> 'INACTIVE';
Many possibilities are there if log is not shipping from primary to standby database. May be a password file issue, may be not a proper network connection or even no proper communication between primary and standby. Kindly look into alert log of primary and standby, use the views like v$archive_dest_status, v$dataguard_status etc to proceed further.