Only 1 appium server

I´ve been trying out appium for some days now and i´m having some troubles with it. I´ve automated a test on an app on Rubymine and was able to run it on 2 android devices through Selenium grid. The problem is that i have to, after i start the hub, register 2 nodes and start 2 appium servers with an udid on default capabilities for each one. I would like to just start 1 appium server and selenium grid would choose which device is available. When i do that the test starts on the 1st device and when i start a second test it just overrrides the 1st test on the 1st device. On the test im not passing any udid. here is my node and what i do to start the hub and the node with 2 instances. I have 2 emulators with android 7.0.

“capabilities”: [
“appPackage”: “cl.entel.appswlsdesa”,
“appActivity”: “.activity.SplashscreenActivity”,
“version”: “7.0”,
“maxInstances”: 2,
“platform”: “ANDROID”
“cleanUpCycle”: 2000,
“timeout”: 30000,
“proxy”: “org.openqa.grid.selenium.proxy.DefaultRemoteProxy”,
“url”: “”,
“maxSession”: 5,
“register”: true,
“registerCycle”: 5000,
“nodeStatusCheckTimeout”: 30000,
“hubPort”: 4444,
“hubHost”: “”,
“role”: “node”,
“nodePolling”: 5000,
“unregisterIfStillDownAfter”: 60000,
“downPollingLimit”: 2,
“debug”: false,
“servlets” : [],
“withoutServlets”: [],
“custom”: {}

I start the hub with: java -jar selenium-server-standalone-3.5.3.jar -role hub
and the node: appium --nodeconfig ./android.json -a -p 4723 -ca -cp 4723

It would be awesome if selenium grid chose an available device. Thanks!