When my Antminer X3 first arrived, I was experiencing connection issues for any pool I directed my X3 to. Since then, I have successfully connected to both a Bytecoin and ETN pool. My problem was caused from me not including a specific difficulty in the worker input section. Including a difficulty level is something I never had to do in the past for any of my previous Antminers. If you plan on using the same pools that I used, then change the wallet address to your own. I also increased the frequency of the X3 to 475M which lead to an increase in my overall hashrate from 220 KH/s to 270 KH/s. If you plan on overclocking your X3 always provide adequate airflow and routinely verify the asic chip temperatures.
ETN Mining
URL:stratum+tcp://etn.fairhash.org:8888
WORKER: ETN Wallet Address.3000000
PASSWORD:x
Bytecoin
URL:stratum+tcp://us.bytecoin-pool.org:8888
WORKER:Bytecoin wallet address.3000000
PASSWORD:x
Antminer X3 Electroneum Pool Configuration with Profits
How to Configure Antminer X3 Cryptonite Bytecoin