For troubleshooting the NodeJs Agent Please find the Steps Below

1. For establishing connection between  Applications Manager and NodeJs Agent Only HTTPS Port of the Applications Manager Should be used
   
2. For NodeJs Agent Version on or above 2.0 Configuration file apminsightnde.json should be present for more details please refer this link .
   
3. Ways to verify whether the NodeJs Agent installed properly or not
   
1. A Folder name apminsight will be created under node_modules 
   
2. An entry of apminsight will be available under package.json
   

If either of the conditions didn't get meet please reinstall the nodejs Agent in the Application..

1.       Check whether any proxy is required for establishing communication between Applications Manager and nodejs Agent