@Z0l this may not move you forward much, but the symptoms of our problems are very similar. EmonTx stops sending CT updates to EmonESP. ESP is still online and accessible. My power is single phase though. I think the issue started some time after I added a fourth CT, but that may be unrelated.

https://community.openenergymonitor.org/t/my-emontx-is-unstable

My current status is that it seems more stable after some firmware updates. It’s only been five days so I shouldn’t speak too soon but previously it would stop at least once or twice a week.

Here’s an example where it froze three times in a week.

So it’s fingers crossed for me.