Hello Hcar, I haven't experience exactly the same issue, but for these kind of issues, I think most of them are caused by NAT settings.
To understand your issue better, please provide below information:
IP address of TG
IP address of your PBX
IP address of your phones(If it is an IP phone)
NAT settings on the TG
NAT settings on the PBX
pcap logs captured on the TG (capture during the issue happening)
pcap logs captured on the PBX (capture during the issue happening)
It looks like the original post has been replaced with spam.
Yes, James, you are right. I have reported this to my Yeastar support representative and they have arranged to remove the content.