I just had this same issue today, Solution is to change the URL before trying to install high sierra. you can do so by following instruction on my recently posted thread.
High Sierra “The Recovery Server Could No… - Apple Community
in short, you will need to go into terminal which is under the utilities tab when trying to restore. you are to manually write the following as it is case sensitive:
nvram IASUCatalogURL="http://swscan.apple.com/content/catalogs/others/index-10.13-10.12-10.11-10.10-10.9-mountainlion-lion-snowleopard-leopard.merged-1.sucatalog"
This will allow you to communicate with apple servers and download the OS.
The root problem here is communication due to SSL protocol from my understanding. by changing https to http you can bypass this finally install your OS.
Watch this video if you need help
https://www.youtube.com/watch?v=ouNQS36dIBw
Good luck,
A1