What's the difference between the UAM secret and shared key fields in DD-WRT? Is this the shared key defined in the clients.conf of radius? What should I use?

This one or the one below this default config
# The default secret below is only for testing, and should
# not be used in any real environment.
#
secret = testing123

Or this ( I manually place this )

client XXX.XXX.XXX.XXX {
# secret and password are mapped through the "secrets" file.
secret = testwifi
shortname = dd-wrt
# the following three fields are optional, but may be used by
# checkrad.pl for simultaneous usage checks
}