I have tried several pools. Some located here in China and some in other parts of the world. I had almost no latency with F2pool and thought that would fix the issue but changed nothing. My connection is not metered but this is China and internet traffic is controlled by law at the ISP level. They firewall most of the world turning your internet into more of a intranet. I also think it might be networking. That is why I was thinking of trying a new ISP. However, why does it only cause trouble with the new S9's. Even if I turn a bunch of other miners off. For a while I had all my miners on one internet service. Then I got the S9s and thought it was a bandwidth issue and split them up on 2 separate lines. Then still had the same trouble with the same miners. I can run 30 other miners on this network but not those specific S9's regardless of pool. The only pool I did not try was Bitmains.