Ok, I see the problem, we modified excavator API with 1.5.x versions.
Try this (change btc address in subscribe method):
[
{"time":1,"commands":[
{"id":1,"method":"subscribe","params":["nhmp.jp.nicehash.com:3200","BTC address"]}
]},
{"time":2,"commands":[
{"id":1,"method":"algorithm.add","params":["lyra2rev2"]}
]},
{"time":3,"commands":[
{"id":1,"method":"worker.add","params":["lyra2rev2", "0"]},
{"id":1,"method":"worker.add","params":["lyra2rev2", "1"]},
{"id":1,"method":"worker.add","params":["lyra2rev2", "2"]},
{"id":1,"method":"worker.add","params":["lyra2rev2", "3"]},
{"id":1,"method":"worker.add","params":["lyra2rev2", "4"]},
{"id":1,"method":"worker.add","params":["lyra2rev2", "5"]},
{"id":1,"method":"worker.add","params":["lyra2rev2", "6"]},
{"id":1,"method":"worker.add","params":["lyra2rev2", "7"]},
{"id":1,"method":"worker.add","params":["lyra2rev2", "8"]},
{"id":1,"method":"worker.add","params":["lyra2rev2", "9"]},
{"id":1,"method":"worker.add","params":["lyra2rev2", "10"]},
{"id":1,"method":"worker.add","params":["lyra2rev2", "11"]},
{"id":1,"method":"worker.add","params":["lyra2rev2", "12"]}
]},
{"time":10,"loop":10,"commands":[
{"id":1,"method":"worker.print.speeds","params":[]},
{"id":1,"method":"algorithm.print.speeds","params":[]}
]}
]
FYI, you said you have 6 devices in the rig, the config file is made for 13 GPUs.