System Configuration: 3CX PBX system, installed as the "3CX linux distro" from 3CX. 3CX PRO version 15.5.6354.2 2 SBC, (raspberry PI3), each with about a dozen phones (yealink T21P E2 ,1 BLF per phone) The SBCs and the PBX are all on separate global IP networks (and ISPs). When I reboot the 3CX PBX linux box, everything comes back up. SIP trunks are registered. station to station calling works (both intra and inter SBC). However, all inbound routes fail. External callers get a busy signal. My SIP trunk provider sends me an error message for every inbound call. "A call to your DID nnnnnnnnnn from nnnnnnnnnn has failed at 5:57pm on 02/06/2018 MDT. We received 'CONGESTION' when attempting to route the call to your server or device. This number is configured to route to the peer IPQUAD on the account bozosRus." All outbound routes fail. Even though they are listed as "registered" and I confirm at the SIP provider the trunks are online. Internal callers receive an "cannot complete call at this time" message. On my dashboard, my "Firewall Check" is "Firewall test OK" Upon re-running the Firewall test, All inbound and outbound routing immediately starts working. It seems like a service is not starting in the correct order upon reboot. Or perhaps a dependency is not met? For example, when running the firewall checker, the 3CX SIP server and Tunneling Proxy are restarted and fully operational well before the 3CX media server is restarted due to the delay in the port scanning of ports 9000...9255. During normal boot, the services start in rapid succession.