Hello,
I’m new to FreePBX and asterisks. I’ve set my system up and everything seems to be working fine. However, after about 15 minute of inactivity, I’m not able to make or receive telephone calls. After restarting the system, I’m able to make and receive calls.
I was having similar issues (except connectivity took about 72 hours to fail) and it turned out to be the SIP ALG in my router. If your router has a SIP ALG setting and you can turn it off, do that and see if that resolves the issue.
Also if you dial internal extensions?