There is sometimes hashrate droped to 0 on second rig. I checked miners logs and there were no any diconnects. Just claymore mined dev fee at same time. Just a few seconds, but the graph looks like my rig didnt work for 10-15min every time.
How detailed are your logs? Do you only see events like "dev fee mining", "disconnected" etc? Cause ideally you need to run with a more detailed log and actually see what's going on during those 10-15 minutes.. are there any shares sent/accepted during that time?