At the moment you are providing http not https on port 443. What did you change ? Was that just moving the IfModule statements ?
If so, it sounds as if you don’t have the module installed - which would explain why none of that file was being used when you had the IfModule statement around it.
To test - if you just remove the IfModule statement ( both lines), what does that give ? (alternatively you may need to install the module - yum install mod_ssl )
Bingo!!! 
I already did the installation thing, mod_ssl is there. It looks as if the test in the conf fails. Weird?
odd - not sure why the test for the module fails. Glad you have things working though 
So, the self signed VPS cert was not the real problem, it did not interfere with the letsencrypt cert. The real problem was the virtual host setup: the IfModule mod_ssl.c statement did not pass. Weird.
Thank you so much for your patience and time. And you pinpointed the problem very accurately. Cool!!
Correct. You’re Welcome
To start with you had the whole of the domain config wrapped in the “IfModule mod_ssl.c”, so it was ignored.
When you reduced the “IfModule mod_ssl.c” to just the “SSLEngine on” and cert details, that got ignored - and hence it was only providing http on port 443.
One you removed the “IfModule mod_ssl.c” test altogether, it was all read, and hence worked.
I’ve no idea why the “IfModule mod_ssl.c” test failed though - lets see if anyone else knows why.
Correct analysis. But the mishap was caused by the "IfModule mod_ssl.c" test in the vhost conf file. The test failed, hence the configuration was not executed. Any idea why the test fails??