I didn’t have any local (to the asterisk server) extensions so this wasn’t an issue for me. However if you check my link above (NAT - That Age Old Issue) there was a comment in there from andres696 about adding “media_address” to the endpoint config. This needs to be done for each endpoint however. The file pjsip.endpoint_custom_post.conf is used here.
However Andrew (Developer) then mentioned that FreePBX is doing this already however I noticed things work when I did this as well just as Andres mentioned. However this wasn’t going to work for me due to the number of extensions I was dealing with.
Hope it helps a bit.