Hey there.
Not sure if you’ve figured it out yet, but I was having the same authentication error as you.
The auth is not the name of the shade group itself, but the name of your system ID.
Let me know if that works!
I know this is an older thread, but hoping someone is still watching!
I am getting the authentication error as well, and I have tried every combination under the sun.
I can open the terminal window (on MAC) and connect to the MyLink perfectly, and it responds with the KeepAlive message every 15 seconds.
But, I am getting the authentication error. I have verified the settings using the “Get Integration Report” from the App.
System ID : Test
IP address : deleted
System pin : deletedCB1128D5 Awning
Target: CB1128D5.1
Name: Awning
**COMMAND SENT:**
{"method": "mylink.move.down", "params": { "targetID" : "CB1128D5.1"}, "auth": "test", "id":1 }
**ERROR RECEIVED:**
{"jsonrpc":"2.0","error":{"code":-32000,"message":"Authentication failed"},"id":1}
I found the issue. Evidently the API is incorrect in the syntax of the command.
The “auth” parameter should be inside of the “params” argument list.
Instead of
{ ”method” : ”mylink.move.up”, ”params” : { ” targetID ” : ”AABBCC.5”} , ”auth” : ”mylinksystem” , ” id ” : 1 }
It should be
{ ”method” : ”mylink.move.up”, ”params” : { ” targetID ” : ”AABBCC.5” , ”auth” : ”mylinksystem” } , ” id ” : 1 }
REF: Integration_API_Rev19.pdf (page 15 of 24)
Hope this helps someone else, and maybe the API can be corrected!
What methods does the doc specify beyond:
mylink.move.up
mylink.move.down
mylink.move.stop
Lots of methods - note, all methods do not work across all interfaces - which ones work on each interface type is described in the document.
Bumping a really old thread… I’m very interested in controlling a new mylink/RTS install that is going to appear in my home shortly. Can I get a link to the Somfy API documentation? was an App written to perform device discovery?
A little help to refresh where this all landed would be greatly appreciated! 
Sorry, bumping this old thread again. I’m looking for the API documentation. Is there anybody who can help me get it? I’m not a ST user, but I developed an integration for Somfy Developer Mode (EU) and US users are asking me to support their gateways too. No reaction from Somfy on their Synergy API site. Did find some info here and there, but I want to add stable, full support. Who can help? Thanks in advance.
@JR90210 @matthewsfamily0914 Tagging you guys because it seems you had access to the documentation.