Solved Slave Bridge PBX can't see presence of just 1 location

[johnporteous]

Hi All,
I have a weird situation that arose this weekend when I migrated an existing PBX to a new server and changed the OS.

In this issue, there are 3 self hosted PBXs, geographically spread. Prior to the migration (done a restore on the new VM & OS and worked a charm), all 3 PBXs could see the presence of one another and call with zero issues.

Here is how I have it configured (when I say 'can see' I mean extensions are listed in the phonebook etc).

PBX A - Is Master to PBX B and Master to PBX C. Can call and see both B and C
PBX B - Is Slave to PBX A and Master to PBX C. Can call and see both A and C
PBC C - Is Slave to PBX A and Slave to PBX B. Can call both A and B; can see PBX B....BUT Cannot see A.

That is the issue; PBX C cannot see PBX A.

When I restored, I simply changed the IP of the Bridge where required but it didn't seem to like it so I deleted all Master and Slaves between the 3 and started again. In fact I have done it several times, methodically going through settings to ensure I had missed any, done side by side comparisons of settings for the same reason. Everything appears to be exactly set correct, just the presence won't work.

The firewall passes tests, no issues making outbound calls, rules are correct as tested calling between all PBXs.

I had this issue a couple of months ago and it was cleared by simply adding :443 once. This time around as it's a migration, as part of the new install from 3CX you have to nominate the HTTPS port which I accepted as default 5001. I wondered if that can be an issue, but it's not because PBX B has been set with the FDQN:5001 and can see PBX A.

I hope that makes sense, please feel free to check with me if you need further info. I'm at my wits end trying to get this one resolved, and would sincerely appreciate any help you can offer me.

 

[SweetAction]

That's exactly what I'm doing, and it's driving me nuts LOL

Break it down.

Can you access by IP but not FQDN? DNS issue.
Not be IP? Tracert is your friend - where does it die? Azure Firewall on PBX A? Somewhere else?

 

[TheodorosG_3CX]

As @SweetAction mentioned those are the steps you need to follow and check connectivity. This is definitely a firewall issue, also check whether there is any DPI on the firewall.

 

[johnporteous]

Sorry, have been to busy to update. I had already done the actions SweetAction mentioned, tracert didn't even get to a first step. So I then ran netstat -ano and it showed that the VM is not listening on Port 5001. However the Azure firewall rules have that open; the same as on the other VMs. So that is the only singular difference I can find, and as Windows VM FW/Defender is off I've had to submit a ticket to Microsoft to work out why port 5001 on PBX C is being blocked.

 

[TheodorosG_3CX]

Seems you have found the solution Let us know the results

 

[johnporteous]

I sincerely hope so, tired of this niggling issue - one of those that is not up there as an essential or urgent task, but wanting to fix it nonetheless. It's good to have the community support in times like this, much appreciated. I'll update it as soon as I get some feedback from Microsoft (that will be Xmas then LOL).

 

[johnporteous]

Well, the issue has been resolved and it was a piddly little setting (which I don't know how it there with that setting as I know I didn't do it); it was simply the LM Host file had the old IP in it.

And not sure how long I would have taken to find it, it was thanks to @kieferschild who kindly done an Anydesk sesh with me.
Greatly appreciated; I owe you a beer - you need to come to Thailand to collect LOL

 

[TheodorosG_3CX]

Great news, glad to know it is resolved