Establishing a data connection controller-server-controller, how?

Question

Telephony

Good afternoon!
At the dacha there is a controller from ab-log.ru MegaD, a wonderful thing, locally within the reach of Wi-Fi everything turns on and off.
But there is no automation of algorithms for turning heaters on and off, etc.
This requires a server, ok, it would be possible to locate it locally, but then how to send instructions to it remotely? Communication in the country is used through the mobile Internet from Beeline (IP is dynamic, respectively), renting a server is not a problem, but then how to establish their relationship, because access and speed restrictions are also present (not a stable connection).
Ps All normal people use a rented VPS / VDS server, which calculates all the readings and sends instructions for the subsequent operation of the controller.
I really want to get an answer to solve this problem.

Answer 1

Try to organize a server on Rasbery PI. If the server needs to take some instructions, then you can put it on the PI client, for example, DropBox or Gdrive, and synchronize the file. On PI, write a script that will check for changes in a file or the modification date, and perform the actions you need.