You can limit the range by editing the server.xml file
To your second question…I have not looked at this in a bit…but I believe in the setting you put it to select from the port pool dynamically. So it just select a free port in the pool you select.
What is the name of the config?
In RTP Part there is only 2 items which are the starting port and allow sharing port
I have done it that way, actually setting UDP Ice Candidate for WebRTC won’t ask you to specify a port number, it will be done dynamically unlike the TCP Port
Please contact the support team for further clarification. The pool can be adjusted in the manager or editing server.xml. It can be increased or decreased using the start UDP port 6970 but will end at 9999.