The problem is not solved. What I observed: On gear-shifting or gradient change the resistance over- and undershoots the target resistance and wobble for a few seconds. You can see this e.g. on the Alpe de Zwift climb:
I was focused on a constant pedaling with constant power, but the unexpected resistance changes made it impossible.
Wobbling power can also be caused by using too small of a physical gear on the bike. What gearing are you currently using (chainring size and cog size - assuming 14t Zwift cog but if not please check number of teeth)?
Wahoo recommends using as close to a 3:1 ratio as you can get: https://support.wahoofitness.com/hc/en-us/articles/16865097915666-Virtual-shifting-with-Wahoo-smart-trainers
If the physical gear is too small, you can get some strange results.
Hi Paul, as mentioned above, I use an original Kickr Core 2 with Zwift Cog and Zwift Ride Frame. No modifications were made.
Sorry I fixated on your comment about a gravel bike! If you’re not seeing dropouts in the TrainerDX log report then you should pursue the problem via Zwift or Wahoo support
What are the possibilities to get Trainer + App logs ? Only TrainerDX ?
Application logs are where you would look for problems, which are available on every platform that isn’t Apple TV where you are helpless to troubleshoot anything yourself. However Zwift support has access to those logs so either you make use of their support service or you run the game on something else like a phone, tablet, PC, etc. A test with the app running on a device that gives you game log access might be interesting.
Thanks a lot for that information. So I install the Zwift App on my Android Tablet (hope it works with Graphene OS) and make a test ride next week.
Unfortunately the ride experience with my new setup (Kickr Core 2 + Zwift Ride) is worse compared with the old setup (Kickr Core One + Gravelbike + Companion App) 
My impression is that the older version of the Kickr Core is the most trouble free trainer when using virtual shifting. If you still have it, putting the Zwift Ride on the old trainer would also be an interesting test. But you would be back to pairing via Companion due to its limited feature set, unless you run the game on something other than Apple TV.
Unfortunately I does no longer have the old trainer. And my LG smart TV does not support installing the Zwift App and I depend on the Apple-TV.
I’ve contacted the Zwift Support. They gave the advice, to check BLE and other devices like fans. It is possible, that the fans I use interfere the BLE connection (see “Troubleshooting BLE and ANT+ Signal Interference” on the support pages). I will check this next week.
Are there any certified fans, that does not interfere BLE ? It it save to place a fan from the Zwift Shop (JetBlack Trainerventilator or Wahoo KICKR HEADWIND) between Apple-TV and Kickr Core ?
Did they say they are seeing Bluetooth disconnections in your logs?
The easiest way to rule out the fan would be to unplug it and do a ride without it.
Another test you could do is pair via the Companion app to see if it’s stable with the current trainer. I understand you don’t want that long term but it can be a useful troubleshooting step to isolate where the problem lies.
I would also make sure that tvOS is up to date on the Apple TV (in the Software Update setting).
I did not test with my Android Tablet, but the BLE interfere was an advice of the zwift support. I will test it next week by placing the fans out of the direkt line between Apple-TV and Kickr.
Saturday I do a ride in real life: Eroica Germania in Eltville 
You should be able to pair the fans via Ant+ from many HRM straps or trainers. I just checked and the Kickr CORE supports Ant+ and Ant+ FE-C.
I have what Paul considers an unusually large amount of devices and it is working.
The one peculiar thing I notice now using either BT4 or BT5.4 is that only every second gear actually makes a change. I am currently using Tacx Neo3m which allows connecting all of the trainer functions via wifi while using Virtual Shifting. The Tacx has a little “clunk” to simulate the chain moving during a shift and I only get that and a change in resistance every 2nd.
As far as interference…
I have trainer and Zwift connected over lan(Tacx Dircon adapter).
Bluetooth handles Zwift to Play, Click, CORE/HRM, Steering.
Ant+ FE-C handles trainer to Elite Rizer incline simulator, Elite Aria fan on speed control.
Ant+ FE-C handles CORE to Wahoo Headwind fan on core temperature control.
I also have a tablet and phone in the same room with BT on but not used for Zwift. Also some smart switches on 2.4Ghz band. Also a TV that has BT though I don’t know if it is transmitting anything. Oh, and some other Garmin devices that can use BT and I don’t know if they transmit. Oops forgot some BT enabled office equipment within BT range.
So they CAN all play nice together. Whether yours are would require some process of elimination testing but in a modern home to say all sources of interference need to be eliminated is a joke. Some fault tolerance needs to be incorporated into the systems.
How many BT devices are in use in a pro Peloton? “To avoid interference please ride a minimum of 3 meters away from other riders!” Lol
When I was using BT4 with a Justo2 with resistance over Bluetooth I constantly had loss of resistance which caused loss of VS. Switching to a BT5.4 dongle got rid of that problem. I probably would have stayed with the Justo2 but the Neo was already ordered. I didn’t choose Wahoo only because I want incline AND analog steering. I had a Wahoo v5 which worked great other than connecting to the Elite Rizer.
Paul has stated BT5 has twice the bandwidth as BT4. This may matter regardless of if the BT radio is used because all the Zwift to game devices communication is processed through BT. Using wifi or lan for the trainer just provides a transport layer for those packets.
Customer service for many companies operates on the “works for others, you must be the problem”. “Have you set your trainer up in the middle of a Faraday cage with only 1 Click controller after a fresh reinstall on all devices? No? Well then are you even trying!?!?!??!?!!!?!!?!”. To some extent this “it is working for the others” is likely true but ignores the ones who give up wasting so many hours to get things working perfectly and just accept good enough. Whatever is causing my “every 2nd shift” is an example. “Must be interference”, ah yeah righto there bud, every 2nd shift consistently for an hour ride, yep uh huh, def interference.
Edit I found I had the shifting set to ‘Climbing’ in the ‘Hardware’ settings tab. I remember trying this during a climb portal. I switched back to ‘Mixed Terrain’ and now it shifts normally. Just some Zwift weirdness.
While I am not using a Wahoo I can comment on BT interference being your problem as suggested by support.
Last night Zwift updated and I find updates or changing which BT device I use on the laptop (a 2012 Gaming laptop with Windows 11) can cause connection difficulties. The trainer would not connect over LAN/wifi. The option was available for Power but would not connect and the option of LAN was not available for resistance or cadence. I restarted Zwift, no change. I didn’t feel like restarting the laptop which sometimes works plus in the name of science wanted to try a ride using just BT so I connected the trainer via the BT5.4 dongle to Zwift.
After the ride I analyzed with TrainerDX. I had no BT drops during my ride. 7 BT devices and 2 Ant+ fans in use. Also a BT cadence sensor on the crank not in use but likely transmitting. Same as I mentioned last post I did have some VS shifts that changed the number on-screen but did not register on the trainer but it was not every second one just random.
Edit power cycling the trainer is what got LAN working again.
The advice about possible interference through fans did the thing. I purchased a Honeywell HT900E within the same week I purchased the used Zwift Ride + Kickr Core 2 Set. The Honeywell isn’t shielded and is obviously the reason for the problems. After using the older fan (with shielding) the problems vanished.
I think, I’m going for a Wahoo Kickr Headwind
Thank you very much for your support.
Glad that has remedied the issue. That fan must be very noisy on the electromagnetic spectrum. If it is not using a Bluetooth remote any 60Hz noise should usually be so far out of frequency to not affect 2.4Ghz.
I figured out what was causing my weird virtual shifting issues with skipped gears. I still had Zwift set to the ‘Climbing’ gear option from trying it during a climb portal. I switched back to ‘Mixed Terrain’ option and now it shifts normally.
@AlanZ is there any other investigation ongoing or some info I can provide to help on this? I did a free today after some weeks of only erg workouts and again that gear 15 was way too hard. This time it did not “reset” during the ride so I had to move to gear 13 or 14 (14 seemed also a bit harder than usual)
Some data I noted during this ride.
Gear 13 - 85 rpm 160 watt
Gear 15 - 85 rpm 320 watt
Previously before all the issues I would ride gear 15 with 85 rpm at around 200 watt
I am having similar issues for about 2 weeks or so. I will do some testing when I can in the next few days.
Having similar issues - within 30 seconds into a race my kickr core loses resistance and I spin out and cry at the side of the road.
So you’re saying I simply go into the wahoo app and change the wheel circumference to any approximate number?
thanks and ride on.
That doesn’t sound like the same problem to me, but it’s trivial to try it and see
