i do have the same issue even i set ssh version 2 in my srx, but NSM still got problem when i try to put SRX in
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Unable to retrieve the Device SSH Key
1. Device Server Down
2. Network Connection Down
3. Wrong Device Ip address
4. Device interface not management
5. Device SSH off or Wrong SSH Version
all above suspect problem is OK in my enviroment, but how comes still cannot
NSM version : 2010.4
SRX version : 10.2r3.10
Thanks
Tony