@Okiedoc 

Did you purchase the devices from the local Amazon site or from an Amazon site in another country? 

These models are TP-Link SubG devices that operate exclusively within the specified Sub-1G band. Different regions support different frequency bands.

If the product is purchased from another country, there may be compatibility issues even if they're the same version. Typically, devices sold locally are customized for the local market, so if a version is not widely used in your area but it is bought from an official channel, it is likely that it was specifically tailored for local distribution before being shipped.