I want to be able to control the trainer in Erg mode to run the workouts. I have a Samsung S7 Edge with the Xert app and a laptop with an USB ANT + dongle.
You will use the Samsung Edge with Xert Mobile running in “Workout Mode” to control the TacX Vortex. Settings are a bit confusing. Play with PowerMatch (try Off, which seems counterintuitive to me). The Laptop (assuming internet connected) can be used to show the Remote Player during the workout to see the details of the workout. The USB Ant+ dongle is irrelevant (unless you want to run Zwift or similar to make the workout more fun - in that case, you should disable workout control from within Zwift for this session) in this configuration.
The second mode of use is where you are free riding or running an erg workout in Zwift or Sufferfest, etc and you want to capture the activity data for Xert. In that case, the dongle is essential to capture and control the Tacx. The Edge with Xert Mobile should be used in passive “Activity” mode in this case, just recording the results of the free ride or workout.
Hope this makes sense. Took me a bit to figure out all the permutations, including which sensors (actual power meter on bike, power meter from my KICKR, ANT versus Bluetooth etc) to use when and how.