There are numerous similar threads but none specific to this, so here goes.
Below is the body of an email from me to Zwift support. It is responding to their initial recommendations. The email was rejected and returned with a we don’t do emails response.
First, I have been battling this for weeks. The only consistency is no consistency. I can ride one day or several with no issue and then out of the blue, trainer resistance is way out of sync with the game or an outright Bluetooth connection drop, or some combo of both. After the information provided below I have to conclude that interference is not the issue. If you don’t agree please offer any further steps that could be taken. I have tested the trainer with the Saris App (Phone at same distance from trainer as ATV) in ERG mode for extended periods of time without any disconnections and unexpected performance. I also tested for several rides on Rouvy with consistent results. I have spoken with Apple support, effectively what they said it is up to App developers to stay up with them, not the other way around. I have reached out to Saris support, but have not heard back yet. But when the trainer acts fine on their App and Rouvy I tend to think the issue is not in that direction.
So, please parse through this and see if you can give me any ideas what to do next.
TP-Link C7 dual band router - 2.4 Ghz radio section turned off
Apple TV 4K - operating on ethernet connection - Software update version 14.3 (18K561)
Zwift Game version - 1.0.60639
Trainer - Saris H3 Firmware version 31.062
Game connection-Bluetooth direct with Apple TV. Tested thru Companion App no improvement.
Zwift Companion App, Bluetooth bridge turned off.
Phone- iPhone 7 iOS 14.3 Bluetooth turned off.
Environment- 2.4 Ghz WIFI radio turned off. Any and all Bluetooth devices within a conceivable range turned off.
Distance between Apple TV and trainer, 60". Has been tested down to 24".