If you use the same AppleID, you get to keep all the apps you bought.

I have six (?) Macs/phones all using the same ID.

Is there something wrong with using Synology’s built-in reverse proxy?

Sucuri?

You don’t have wordfence and auto-updates turned on?

Here’s what I think happened: Everything you see is something you did.

The subdomain you host points to your IP … or at least it did. Your ADSL IP address has changed and your domain is now pointing at someone else’s IP as their ADSL has claimed it.

Ping the subdomain and see the IP address. Now go to https://whatismyipaddress.com/ and see what your IP address is. They’re different now, right?