Receiving "Socket connect failed: Connection refused" for 3 miners. Bitmain replaced Controller board for 1 of them but now refuses to send me replacement board for the other 2 and are not replying to my ticket for over 3 weeks. Beware of buying into this crap. This is the end of bitcoin and antminers to me.
That's probably because the "Socket connect failed: Connection refused" error usually means that your pool configuration is bad (or possibly your networking). Sometimes it can also be the firmware. What pool(s) are you using? Do you have any other AntMiner S9s that are working? What are the firmware versions for each of the miners (Logic Version from the System -> Overview tab)?