I used Duplicator on one site with all the same versions/setups and it worked perfectly.
My second site was much larger, and I ran into this when trying to set up my subdomain: "504 Gateway Time-out... the server didn't respond in time" so I contacted the hosting company to see if my max_execution_time in PHP configurations could be increased beyond 6 minutes. Instead, they opened a specific port that stays open without limit and kept it open, letting me go through that, until deployment was complete. It took 8 minutes, instead of 6.
Everything looked great, the test at the end looked fine. They closed the port and I said goodnight.
Then, the problems began. By using that port, the port number was somehow added to the URLs of everything in my database, including the basic site address. If I typed my subdomain name into the browser window and hit Enter, it was immediately replaced with the same URL plus the port number (www.subdomain.maindomain.com:81/wp-admin) and in Google Chrome, I'd get a msg: "Oops, Chrome cannot connect to.." (URL with the :81)
Level 1 techs worked on it and I was able to get back in, but afterward the images were all broken-linked, as each had :81 in its path.
After hours worth of wrangling around in my site's intestines, Level 2 techs at the hosting company manually removed the :81, images were back, but over and over, login problems still persist.
Probably didn't need all of the above to ask my main question: Have you ever before encountered the deployment through a special hosting port rewriting the URLs of content to include their port number? (convoluted sentence...sorry)
I wish I'd tried your suggestion for adding a line to the .htaccess file first, instead of hoping for a time extension from the hosting company.
I will greatly appreciate any light you can shed on this (and will wait to hear from you before I start over from scratch with these two test subdomains). Thank you