Here is a guide how to configure SNMP on F5:
https://support.f5.com/csp/article/K52219241
make sure you read it first.
So a snmpwalk from you source Solarwinds server does not work?
when you say "Now if I go to any of my F5 devices and perform the same snmpwalk" you sis a snmpwalk from the F5? or from Solarwinds server? Try a snmpwalk from a Solrwinds server. There is an exe file that can do that.
Note: By default, SNMP is enabled only for the BIG-IP system loopback interface (127.0.0.1).
Make sure you have this:
"
- On the Main tab, click System > SNMP > Agent > Configuration .
- In the Client Allow List area, for the Type setting, select either Host or Network, depending on whether the IP address you specify is a host system or a subnet.
"