One way audio after idle time

I am having a strange issue with my setup.
I have my Trix behind a firewall, all nat settings to the conf files etc.

I am using two separate trunks, on for incoming and a different voip provider for outgoing. If I do not get a call for some time (several hours), the first call comes where the person on the other side hears me, but I do not hear them. I hang up and they call again withing 10-15 seconds, the call is fine. I can go ahead and make calls, receive calls for the next hour and everything is fine, but if I let some time pass by the problem occurs again. Sometimes 10 minutes later, sometimes 3 hours later, the one way audio returns.

The same thing will happen on outgoing as well. First call I make I do not even hear the dialtone the PBX sends, nor do I hear the ringing on the other side. I see that my SPA942 says Session Progress, then Connected. I hang up and make a call again with success.

Any help would be marvelous.

This is not a FreePBX issue. You are unlikely to get help here.

You should start a thread in the trix forum and tell more about your network.

Sorry about that.
I have both systems and seem to have logged into the wrong forum.