Which ports for unreal pixelstreaming

Question

I have Unreal Pixelstreaming set up on a windows server in aws and all works fine. Security restrictions require me to move the windows server behind an AWS Networking Loadbalancer. I can specify individual ports in the NBL, but not ranges. The webrtc player of unreal seems to be randomly choosing ports for UDP on top of the configured ports 8888, 80 or 443 - they change when i reload the page. How can I set up listeners for this in the NLB?