Your Solarwinds is correctly configured to only use SSH-v2 (congratulations!), but your devices are using V1 (boo, hiss!).
The right thing is to remote into each one and configure it for v2 only, deleting the v1 lines after proving v2 read-only or R/W access is successful. This includes your security solution (ISE preferably, but Radius or other secure solution tying your credentials into your A.D. structure).
The wrong thing to do is reconfigure your NCM to allow SSH-v1. Don't do it.
Cisco 3750's support SSHv2, it was supported by most, if not all, Cisco devices long before the 3750 even came out! Rather than working on getting v1 to work, which is very insecure, why not move the 3750's over?
You might have to generate a new crypto key, and then do an "ip ssh version 2" and you should be set!
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