Filemaker PHP Web Publishing - Synchronising not working with new host address

We have a windows server setup in our premises where we host our FileMaker server (FMS 15).

We are thinking of moving the host into a cloud server (FMS19).

We have taken the latest backup of our databases (from FMS 15) and uploaded it into the cloud server (FMS 19).

The extension of the backup file is .fm12 so it was uploaded easily from FMS15 to FMS 19. Database structure remains exactly the same and the connection from FileMaker pro is also working fine.

The Issue

One of these databases (database db_fm for example) is connected to our website. A cron job runs every 5 minutes on our website that syncs information from the website's database (db_website) to that of FileMaker's databases (db_fm). The sync uses FileMakers “PHP Web Publishing”

After uploading the latest backup in the cloud server (FMS 19) I have changed the host address in the config file

i.e; I have changed the host address from

//host for our internal server
$FileMakerHost = 'http://77.**.***.40:8080';

//host for cloud server
$FileMakerHost = 'https://a*****2.fmphost.com/ ;

Database structure and the password for the Filemaker database remained the same. So have not changed anything else other than the host address.

The synchronization works with the current database (hosted in our windows server FMS15) but it is not working with the new host (hosted in cloud server FMS19).

After changing the host address we have created a test subscriber. That record should be added to the FileMaker database (i.e the one hosted in cloud server). But there is no new record created.

Can you please assist me with what can be the issue? I cannot think of anything else other than changing the host address. What can I do to make it work with both servers?

FYI

The sync uses filemakers “PHP Web Publishing” The cloud server
(FMS19) is also in windows and PHP publishing engine is enabled
Our site is built with laravel.

Solution

The main problem was the new host address was https. The sync was working for HTTP address not https.

Following are things that we have done to make it work

We added an outbound rule in our webserver (where our website is hosted) on port 443.
Then we have reset the cache via ssh. systemd-resolve --flush-caches . Because automatic redirect was cached

FMPHOST (The hosting company) suggested us, to test from PHP so that it can get any response from https://a******.fmphost.com/ or http://a******.fmphost.com/ (Use curl commands to prove port is not blocked between the web server and FileMaker Server)

Thank you