Does Dashr require a constant wi-fi / network connection to work with rostered athletes?

No. Make sure you log into the app while on network/WIFI so that your phone/tablet can download the updated roster before going out on the field. That should get it so that athletes can be checked in and then their results are saved to the history tab.

Once back on network, open the app – go to the history tab – and hit the upload button at the top to send your results to the online dashboard.