Issues with DNS

[mark65]

I have an on-premise system (18.0 Update 5) running on a Windows 10 machine with a direct connection to the internet. Every few days I lose the ability to make outgoing calls. If I go into Windows network settings and change the DNS server for my connection I can make calls again for a few days. I am repeating this cycle at least once a week. I am not using one of the approved SIP trunk providers, but not sure that has anything to do with it.

 

[SteveITS]

Before you do that next, is the server accessible on that adapter? IOW is changing DNS maybe resetting the adapter/driver and that's the actual issue? Or is DNS not working but connectivity is working (ping 8.8.8.8) until you change DNS?

 

[mark65]

Everything else continues to function. I can receive incoming calls. I can open a web browser and browse the internet, however the machine does have 3 NICs so I can't be sure it's using the public IP to get out. I can test that by unplugging the other NICs next time it happens. For whatever reason it's almost like the DNS server is blackballing communication from 3CX.

NIC 1: Management VLAN
NIC 2: Voice VLAN
NIC 3: Public Static IP for SIP Trunk (I've confirmed 3CX is using this NIC in settings.)

 

[SteveITS]

Try nslookup at the time:
nslookup example.com nameserverip

and:
tracert nameserverip

 

[mark65]

I wanted to update the thread in case anybody is searching. Using the suggestion above I discovered Windows was routing traffic to the SIP provider through the LAN adapter instead of the WAN adapter. I was able to resolve this by disabling Automatic Metric.

1. Navigate to: Control Panel>Network and Internet>Network Connections>Your WAN Adapter>Properties>TCP/IPv4>Advanced
2. Uncheck the Automatic Metric Box
3. Manually enter a low number. A metric of 1 worked for me.

 

[cydigitalnet]

I wanted to update the thread in case anybody is searching. Using the suggestion above I discovered Windows was routing traffic to the SIP provider through the LAN adapter instead of the WAN adapter. I was able to resolve this by disabling Automatic Metric.

1. Navigate to: Control Panel>Network and Internet>Network Connections>Your WAN Adapter>Properties>TCP/IPv4>Advanced
2. Uncheck the Automatic Metric Box
3. Manually enter a low number. A metric of 1 worked for me.

That was very helpful, @mark65

Thanks