Trouble Understanding Opus Encoder

I'm trying to stream audio to a device (ESP32) over wifi using opus
encoding. It works however I would like to reduce the bitrate to try and
get a greater distance over wifi. It appears that the bitrate variable for
opusenc does nothing. I seem to get the same stream whether I put bitrate=2
or bitrate=32000. I've tried different bitrate types as well. Below is a
typical pipeline that I'm using. I'm sending the stream to a broadcast over
UDP

gst-launch-1.0 -v jackaudiosrc connect=0 ! audioconvert ! audioresample !
audio/x-raw, rate=8000 ! audioresample ! opusenc bitrate-type=cbr
bitrate=32000 complexity=5 max-payload-size=1000  !  udpsink
host=192.168.1.255 port=8000

What am I doing wrong? I am sending low frequency sounds so can tolerate
low bitrates.
Thanks for any advice.
Jim