First, is there a specific reason why you are using the virtual bridge? In case you want to communicate with the world, you’d end up with at least two NAT boundaries. Inside a LAN, a simple macvtap bridge should be more straightforward and the rest would also be easier.
Instead of showing parts of your firewall configuration, you should show the actual SIP communication (sip set debug on, or pjsip set logger on). There’s not much we can see here and any help would be guessing only.
The problem is the I/Client connect to the Main Asterisk Server no problem but I dont hear any sound from the server.
If I play a file to the client via the Proxy I hear sound (tells me forwarding is correct) but for some reason I cant get sound back going to the main server -> client.