My antminer s5 produces lots of hw when start hashing because pool tells the miner to set difficulty to 4096....way too high!
It reduces after a while...minimum diff on pool worker settings is set to 1024 too....how can i get rid of the 4094 difficulty?
It should run just fine at high difficulty and that should not cause any hardware errors at all. This is odd.
It will go to 4096 diff after it serves you 1024 diff and your S5 finds many 1024-diff proofs of work very quickly. Normally I wouldn't expect this to happen, but rather that you would get 1024 diff all the time. It could be caused by batching proofs of work so sending them to the server is delayed, the way the old Avalon machines did it. But it's a really bad idea and I don't think any ASICs do this nowadays. So I'm not sure why this happens to you.
Normally I wouldn't worry about the difficulty going to 4096 for a few minutes and then back to 1024. It should not be a problem at all. But you say you get a lot of hardware errors. Are you sure they happen when mining at difficulty 4096 and not at 1024? It doesn't make any sense at all. On the other hand, it wouldn't be the first time an ASIC machine behaves in a strange way.