Using 4G backup / ngix Web Service fails shortly after it starts when 4G connection enabled

[sysadmin_at_lca]

Can anyone advise how they handle failover for 3CX phone systems, for the Internet connection?

My cunning plan, when a customer had a line fault that caused their ADSL to drop to put a 4G connection in place so that the phone system could still work via 4G, and the desk phones could reach the PC. That way ONLY the phone system data would work across the 4G and the kids/users trying to use Netflix/YouTube wouldn't kill the limited amount of data on the 4G service.

However on deploying this and getting access back to the PC with 3CX on it I found I couldn't reach the web interface (locally) and noted that the ngix web service had stopped.

I could start it, but within seconds it would stop with warning event log saying the service had stopped (code 2?).

I then thought the phone system had an issue at the same time as the ADSL service and proceeded to perform all kinds of troubleshooting on the 3CX system, to the point where I've uninstalled and reinstalled 3CX a LOT of times. Now I'm stuck that I'm getting a generic "licence activation failed" regarding an adaptor issue, but having completed fresh installs, etc, it's not related to restoring a backup or installing fresh, etc.

So:

• root cause: primary internet not available, so attempted to setup a local 4G connection
• secondary cause: ngix doesn't seem to like having a cabled (but not internet active) connection and a 4G connection running at the same time

Any hints would be great.

I think for the moment I may just need to setup the 4G attached to the router in some way for failover purposes, once I actually manage to get the phone system reinstalled.

 

[accentlogic]

Yes, I think you will need to have the router handle the failover. 3CX does not like multiple net work adapters or multiple gateways. Be sure to test your SIP trunk failover if you don't have local dial tone, and you might need tell 3CX that you are using a dynamic IP address. Failover won't be immediate, but will take a few minutes.

Because you are using your local router for failover, you will need some additional rules to deny non 3CX traffic when using 4G.

 

[sip.bg]

If you have network cards with dynamic MAC addresses, you may have license issues, contact 3CX sales in such case.
Generally: on a system with several network interfaces, you may have as many as you want, there should be only one default gateway, the traffic through other interfaces should be routed using static routes with different metric. The address on primary interface can't be changed without reinstalling the 3CX.