It sounds like there is some problem with the V9. I am getting 0.2% reject rate with my S9s and Halong T1
but my Avalon 741s are getting 3% reject rate. That's 15 times greater than the S9s and T1. This is why I
probably won't buy Avalon miners again.
You need to either check you network performance, miner settings or PSU's.
I run over 230THs of Avalons ranging from 721's up to 841's. All have less than 0.8% rejects and yes it is the bank of 741's that are at 0.8, most are around 0.2 to 0.3% rejected.