Thanks 
Interresting, so it may come from my netcode. A possible explaination could be the devfee session that may get a different diff as the user pool. But the devfee sessions are Claymore-style: small randomized sessions that don't disconnect your own pool, so you may encounter a few shares with a different diff from time to time (0.9% of time average) but not a permanent change.
Also strange is that i got this problem reported on CN-Heavy coins, while of course my netcode is the same whatever the coin is (only Nicehash has dedicated netcode).
This is not a big threat since all diff are equivalent in term of efficiency, but that's still a bug. Also check pool side the shares you get are the same as the effective hashrate reported by the yellow report, within a ~2% tolerance, and after a few hours of mining. If you observe a huge result difference, so it could be a critical bug.
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Weird part is that when using fixed diff like 25k with jce-miner, diff changes after some time but same 25k with xmr-stak, diff stays fixed...
Interresting, so it may come from my netcode. A possible explaination could be the devfee session that may get a different diff as the user pool. But the devfee sessions are Claymore-style: small randomized sessions that don't disconnect your own pool, so you may encounter a few shares with a different diff from time to time (0.9% of time average) but not a permanent change.
Also strange is that i got this problem reported on CN-Heavy coins, while of course my netcode is the same whatever the coin is (only Nicehash has dedicated netcode).
This is not a big threat since all diff are equivalent in term of efficiency, but that's still a bug. Also check pool side the shares you get are the same as the effective hashrate reported by the yellow report, within a ~2% tolerance, and after a few hours of mining. If you observe a huge result difference, so it could be a critical bug.
Yeah, true that it isn't a big threat but sometimes miner stays like 7 minutes without finding hashes.
For example I start at 25k diff but it increases (as far as I could see) to 400k...then moving up and down, etc.
Anyways, thanks mate!