Random loss of outbound audio

I know typical issues with this are NAT related but some environment background we have a multi-site vpn setup between 4 locations. The main building hosts the pbx. Up until 3 months ago there were no issues and the system has been in place for 3 years. The remote sites use the wan address of the main site to connect to the pbx and they have no issues with audio. The main site extensions utilize the local ip of the PBX. Intermittently all outbound audio will stop on all the local extensions but again still works at the remote site.

There is nothing relevant in the log screenshot; the warnings are normal

Ill pull logs from the extensions. The logs on the extensions matchup to the timestamps on the server and mention authentication errors.

Here is the log from one of the phones as well as the pbx log when the extension loses audio.

Is any of this helpful? I really need to get this working as the volume of lost calls is problematic.