The reasons for this situation are as follows:

1. Port occupied: Make sure that the bound port is not occupied by other programs. You can use a command line tool (e.g. netstat) to view the ports that are already occupied in the current system, and choose a free port to bind to.

2. Privilege restrictions: If a program tries to bind to a port lower than 1024 (such as 80, 443, etc.), it may fail to do so because of privilege restrictions. In this case, you can try to select a port higher than 1024 for binding.

3. Firewall restrictions: Firewall settings may restrict a program's access to certain ports or IP addresses. Make sure the firewall allows the program to communicate using the specified IP address and port.