@Brian99 

Hi,

I don't know what kind of circuitry is used to make 2 x 110 V from 220 V, as this does not exist where I live, but in countries that utilize real three-phase electricity so-called "phase couplers" exist that are made for the exact purpose of transferring Powerline signals across the three phases.

For example: https://sednashop<dot>com/index.php?route=product/product&product_id=68    (replace <dot> with . )

You could ask you local electrician if something like that exists for the type of electric circuit in use at your place.

  @Brian99 

  @Brian99 

It is technically split phase 220/110 V.  Two 110 V hot lines 180 degrees out of phase - so 110 V from hot to neutral and 220 from hot to hot - very common in North America.

  @Brian99 

Google's search results only show me phase couplers suited for Homeplug Powerline that have connections for three phases. I don't know why that is.