Windows PC power issue with zwift and Saris/cyclops H2 trainer

I have been struggling with my zwift for more than a year now. I have a PC connected to 5GHZ wifi connection and Bluetooth to trainer. When zwifting if i ride steadily at 160w, everything is normal. As soon as i push up watts to say 240w as an example, i can hold it for approx 3 or 4 secs and then the resistence increases (even on 0 or negative gradient) and then pushes me down to low 100s and then it eases off again and i can settle at steady 160w. So i cant push up watts to climb or burst or on training programmes. I have had the trainer in a couple of times and boosted dedictated wifi channel. I have ridden with same PC on an alternate trainer on a different wifi connection and it works normally. So cant be my zwift settings. Can only think its interference on the connection in my home gym or the trainer itself. Anyone have advice please.

Sounds like a trainer malfunction,.either perhaps overheating or the trainer’s braking effect not working properly.

If you test the trainer using the Saris app instead of zwift that might help rule out a trainer problem