Two tests simultaneously on different devices [iOS 10, Appium 1.6.3]

I am writing to you to ask you whether it is possible to execute two or more tests simultaneously on two or more different devices, such as two iPads running iOS 10 and Appium 1.6.3.
I have tried to execute them but here is following error message:

An unknown server-side error occurred while processing the command. Original error: Could not proxy command to remote server. Original error: Error: connect ECONNREFUSED

Thank you in advance,

try with parallel test execution method using testng annutation @parameter

I have solved the problem this way.
Please note that every test runs using a specific port of the iProxy, and the server of Appium works using another port. Both ports are defined through the following command line:

appium -p [appium port number] --webdriveragent-port [iProxy port number]

Two different tests cannot run using the same iProxy port simultaneously, and one of the two tests need to run using a different port from the one used by the other test.

First test

Second test

Yes u r right,

Please send the code.