hello i have problem on receive source port rtp packet

client-ip = 5.202.105.250

server-ip = 194.5.205.33

client2-ip = 188.212.241.46

In the 200 ok packet from client2 ,The value 4002 is set in the audio port

I expect rtp packets to be sent to me from source port 4002, but these packets are sent to me from another source , which is port 55755 in the image below, and I just opened this port(4002) in the firewall.

If I turn on my firewall service, all packets will be dropped. I have to have this firewall

thanks for help me