I had a customer with a juniper j6350 internet router. "Juniper j6350" SystemOID=" 1.3.6.1.4.1.2636.1.1.1.2.20">
It wouldn't take the default template,
To resolve we actually had to put the CLI as the reset command instead of a pre command
<Command Name="Reset" Value="cli"/>
Session Trace showed that this allowed the prompt to change from Unix % to the JUNOS prompt.
The usual template commands would then be accepted and config could download no issues.
Customer explained that he had the same make and model working with standard juniper template,
although there was a difference of the JUNOS version,
Customer believes that the router may have some configuration setting that can enable or disable the UNIX % \ CLI junos prompt behavior.