V5.6.2 - UDP via 127.0.0.1?

I’m testing out moving to v5.6.2 and UDP. I have a python script that’s reading a UBX-F9R and building a PANDA sentence. The code is set up to send the panda sentence to 127.0.0.1 port 9999. I’ve tested this on V3.x and can see the data coming in. Obviously it doesn’t parse or do anything with the data. When moving to v5, after enabling UDP in Agio, I get an error that states: “Only one usage of each socket address (protocol/network/address/port) is normally permitted”

Will localhost work in v5.6? I’ve tried ports 9999,2233 and 2244. The python script is acting as a UDP client. Any guidance in what I’m doing wrong?