Regarding zigbee mesh:
Zigbee lightbulbs may use either the the ZLL (zigbee light link) profile or the zigbee home automation (ZHA) profile.
Most lightbulbs that use the ZLL profile, including Phillips Hues , will only repeat for the other lightbulbs on their mini network. This is in part a security feature.
There are some Zigbee lightbulbs, including the Osram Lightify, which use the ZHA profile, and will repeat for other ZHA devices provided they are drawing current. ZHA handles security differently because there is a central controller.
The following FAQ explains more about range and repeaters: