I tested it in my environment:
1、The standard name of ‘UDP_CONNECTION_REQUEST_PORT’ in the env file is ‘GENIEACS_UDP_CONNECTION_REQUEST_PORT’ (Environment Variables — GenieACS Documentation 1.2.13 documentation : ‘All GenieACS environment variables must be prefixed with GENIEACS_.’).
2、It is enough to choose one of the ways you said (Env file or Config, the former requires the services restart).
We can refer to Link: Stuntman -server ,No UdpConnection Url if someone needs pictures to show the details.