What are you using for config settings on miners?
I use a standard configuration - contents of the file diamond.conf
rpcuser=YYY
rpcpassword=XXX
rpcallowip=*
rpcport=9010
daemon=1
server=1
gen=0
maxconnections=100
addnode=213.229.0.41
addnode=193.77.159.166
addnode=113.168.158.16
addnode=193.68.21.19