issue with using AW Series 4 in gym

I have an AW Series 4 and have an issue in the gym. It plays music that has been downloaded fine through AirPods. However when I try to stream from my Apple Music library it studders. I think the issue is it is trying to connect via Bluetooth or the gyms Wifi to the iPhone in my locker and not getting a good connection to he iPhone. If I leave the iPhone in my car or turn it off the streaming music plays without a hiccup.

Any simple way - aside from turning off the iPhone to stop the AW from trying to connect through it? I have tried turning off both Bluetooth and WiFi on the iPhone but the watch says it is still connected to the iPhone.