Troubles after upgrading

After upgrading FreePBX from 6.12.65-32 running Asterisk version 11 to running Asterisk version 13.15.0,
we are now seeing a problem with phones just randomly showing No Service. Without doing anything they will start working again in a minute or so. We did not have this problem before the upgrade and I do not see any network problems. I have also had reports that when on a call it does not drop the call but they may miss a word or two when on the call. It does sound like a network issue but I have looked and do not see any kind of problems on the network.

I did fail to mention that in the logs I do see these errors: pbx_functions.c: Function PJSIP_HEADER not registered and pbx_functions.c: Can’t find trailing parenthesis for function ‘DB(DEVICE/XXXX/dial’?.

That sounds like a broken installation.

I also failed to mention that this was not a normal upgrade. I upgraded from a 32bit version to 64bit so I did a clean install of the 64bit version and performed a backup and restore to the new server.

Woot - found your problem:

Backup and Restore is guaranteed to fail between different versions of the system. It might almost work if the versions are close, but for a gap this big, you are going to end up with a hopelessly demolished installation.

When I did the Backup and Restore I built a 64bit 6.12.65-32 and performed the Backup and Restore to it. I then upgraded it to