Discovery doesn’t work for MacBook Pro, does for other MacBook

[tim]

I use Ubuntu/Pop_OS! to connect to two macOS computers. Only the MacBook shows up when the local network is searched.

The 2017 MacBook Pro does not. On that computer, under Server settings –> Ports, the NX service is running and “Advertise this computer…” is checked.

I exported the logs and they indicate the service is listening for connections.

What are my next steps to figure out why this computer is not being discovered.

Server: 2017 MacBook Pro Ventura 13.7; NoMachine 8.14.2

Client: Pop_OS! 22.04 LTS; NoMachine 8.14.2

[Britgirl]

Hi, can you enable debug and send us the server-side logs of the affected Macbook, so we can check them? You can extract them using the instructions here: https://kb.nomachine.com/DT07S00243

Attach them here or send them to forum[at]nomachine[dot]com. Please use the title of this topic as the subject of your email. Thanks!

[tim]

Completed.

[Britgirl]

Hi, logs show that that NoMachine is broadcasting correctly. So, we need to understand why your client is not receiving from the problematic Macbook. Either the Macbook 2017 server is not on the same LAN as the client (they must not be subnets), so verify this. And check that the firewall of the 2017 MacBook Pro is not filtering the traffic. You can do that by temporarily turning it off.

[tim]

All computers are on the same LAN (no subnets) assigned ip addresses by the same router.

Turned firewall off on 2017 MacBook Pro and restarted. No change. I’m pretty sure the working MacBook also has the firewall on, but I’d have to check and confirm later. Either way, the 2017 MacBook Pro still doesn’t show up (I am able to connect by manually configuring).

 

[tim]

I just tried deleting and reinstalling NoMachine on both the Ubuntu box and the 2017 MacBook Pro. Same result.

[Britgirl]

We could send you a package for you to install with higher debug enabled for mdns discovery which could allow us to investigate (given that we can’t reproduce it). Are you available to try that?

[tim]

Sure. Would be happy to help and try that.

[Britgirl]

Hi Tim, check your inbox 🙂

[tim]

Hi @Britgirl–

I just wanted to confirm y’all got my set of logs from the higher debug version and that they are what you need?

Thanks!

Tim

[Britgirl]

Apologies for not updating you. The logs show that the player didn’t receive anything on the port where it reads the multicast UDP messages (to know the servers available in LAN). And we’ve previously confirmed that NoMachine is broadcasting correctly on the Macbook server. So something is happening in the middle, and in the middle there is either the network or a firewall which we have no control over.

Did you already try:

disabling the FW completely on your Ubuntu machine?
checking whether the Macbook Pro (2017) machine can see the Ubuntu host and the other Macbook?
checking whether the other Macbook can see the Ubuntu machine and the Macbook Pro (2017) ?

[tim]

Resolved!

Here is what I discovered. As requested earlier, I had turned off all firewalls and VPNs. What I didn’t see or think would be an issue was a filter that was created for the VPN (split tunnel) on the MBP. Even though the VPN was off, this filtering rule remained active, and prevented the discovery. I can’t say as I fully understand *why* this is offensive to the process, but I was able to replicate the behavior to confirm the solution. With the split tunnel filter explicitly turned off, the MBP is discovered as one would expect.

Thank you!

 

[Britgirl]

I don’t know what VPN you have installed on the MBP, but it’s strange that a VPN filter remains active even when the VPN is turned off. Thanks for letting us know anyway.

[tim]

PIA VPN, but I typically only use it when traveling. The filter was for a split tunnel which PIA had me configure about 8 months ago because, I think, npm or maybe docker hub downloads were hanging.

Worse, this morning I went to connect to the MBP and once again couldn’t see it. Turns out, the filter became active again on its own even though the VPN is off. Now I’ve deleted the rule and hopefully this is really resolved.

[Author]

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