1 week old E4 does not work with iPhone

My 1 week old Connected E4 has now had 2 factory resets to try and get a constant connection to my iPhone running the latest iOS 17. I’ll give it a few more hours before I need to at least restart the Bluetooth on both devices. Does anyone have a fix for this please? Otherwise it’s going back to the shop this week, unbearable for an almost $3k watch that it doesn’t even work properly.