Synology NAS provides a build-in functionality to configure your domain like fisenko.page even you don't have a static IP address. You just need to open: Control Panel, External Access, and click on Add in DDNS section.
It works fine until you need to add sub-domains, like blog.fisenko.page, blahblahblah.fisenko.page etc. For some reason, the build-in DDNS settings don't allow to add more than one domain for one service provider. For example, I want to configure fisenko.page, blog.fisenko.page with Google service provide.
Fortunately, there is awesome package DDNS Updater 2
DDNS Updater 2 is a web interface and client to configure and automatically update dynamic DNS hostnames. A variety of providers can be created 'Out of the Box' by the customizable user dialogues, configurable response codes, and protocols. If a protocol still can not set up API compliant, this can be achieved through an additional module. The setup wizard is another new tool with multiple features. These range from the first analysis via functional tests of compatibility with a module up to the completion of a new provider or protocol. New providers or protocols, if the compatibility is provided with a built-in module, can be distributed by import/export function easily via the Community.
To get it worked DDNS Updater 2 needs to be downloaded and installed after that multiple sub-domains could be configured as below
The same configuration needs to be done for all subdomains.
Now DNS is configured but an additional step is required to add HTTPS support. Fortunately, Synology already has built-in Let's Encrypt support. Certificates could be added as shown below:
That's it. Thank you!