I just paired up my Apple Watch with my iPhone 7. I noticed that only phone calls work while my iPhone is turned off and data/messages do not work at all. Only way to use data on my watch is while my iPhone is turned on.
Reading the apple web site suggests that both (watch and phone) need to be connected to cellular network in order to use all features of my watch. For example if I leave my phone at home and go to the park with my watch, only way I will be able to send emails and messages from my watch is if my phone that I left at home is turned on.
Can somebody explain me how this works and which preconditions need to be fulfilled for me to use data connections on my watch?