Redirect old domain to new domain from old server to new server

I’m trying to redirect my-domain/page.html (a static site) from server A to mydomain/page (a WordPress site) on Server B. I’ve tried simple 301 redirects and the redirection plugins but when I go to my-domain/page.html and click on a page link that I set up to be redirected to mydomain/page it doesn’t go to the new url it simply goes to the original one.

I also tried inserting this code: Redirect 301 /page.html https://www.mydomain.com/page into the .htaccess file – (I tried in both domains but not at the same time)

I have no idea how to get this accomplished – any help would be appreciated.