You can also expliciitly whitelist each of the server hosts.
In addition, in FreePBX “context=default” should be throwing an error. Try something like “…=from-trunk”.
The DTMF mode selection may not work reliably as well. If it works for you, good, but if you have trouble with digits not working in IVRs or in Voicemail, you may need to narrow your DTMF Mode selection down a little bit.
Only use “type=friend” if the address you specified can receive calls from your PBX as well as deliver calls to your PBX.
It’s not that I don’t believe you, but until I see the logs where the address is getting blacklisted, I’m not sure I can understand what you are saying. If the host is properly whitelisted in the firewall config, it will not be blacklisted by the firewall.
Try using the GUI for both sides of the discussion. It’s possible that you are looking at two parts of the system that are disconnected at some point.
Your list of trusted hosts in the Firewall GUI should match the fwconsole fw command list. Double check that.
Finally, there has got to be something in your /var/log/asterisk/full logs (or maybe the firewall logs in the same directory) that tell why the hosts were locked out.