It happens because very smart boy - dstm hardcoded fee pool in this miner. When pool (flypool) is down miner is out of work. So I lost more than hour on my farms it is much more than fee. Now I switched to EWBF - it is less vulnerable to such a treats.
Bye bye dstm..
I was trying to figure out what went wrong, it's been stable AF, running few weeks straight and then suddenly all those emails saying that miner has gone offline.
Few hours downtime is not that bad compared to all those months EWBF's made ~7% less.