Network Solutions ssl csr with F5 11.5.1

The only workaround I can think of is what nitass said, use the command line openssl. You can do this on probably any linux box, on the F5, or even cygwin on windows(with openssl installed)

Gen a CSR with a new Private KEY: openssl req -out CSR.csr -new -newkey rsa:2048 -sha1 -nodes -keyout privateKey.key

You will need to import the above privateKey.key into the F5 along with your new certificate. Remove the -nodes if you want to password protect the private key.

If you want to reuse a private key, use: openssl req -out CSR.csr -key privateKey.key -new -sha1