I've set up an OpenVPN between 2 sites. I have 3cx installed at site one using bridged network and I have a PC at site two with OpenVPN also using network bridge connecting to site one. All extensions at site 2 register with no problem and can make and receive calls. The only issue is if either site try to transfers a call. The result is one way audio (site two can hear site one but site one can not hear site two) Any ideas?