How to properly park a domain on WP?

Question

WordPress

Gentlemen, there is an express question on WP. There was domain A, bought domain B. The task is to make it available for both domains. I parked domain B - attached SSL.

1. Change domain in wp settings
   
2. Made a redirect to htaccess
   
3. Added domain to wp-config
   
4. Changed domain in wp-options database.
   
5. Permalinks updated
   

Only the main page works, the rest returns 404. Does anyone know how it is treated?

Answer 1

The task is to make it available for both domains

This is called an alias.
Let the VP also remain attached to domain A.
Remove domain B from the hosting and add it as an alias to domain A.
Reissue the certificate for domain A, specifying domain A with and without www in aliases, as well as domain B with and without www.
Seems like it should work without a problem.