Looking for help troubleshooting a peer discovery issue

[YrbkMgr]

Guys, I'm new here and I need help troubleshooting a problem that is out of my depth because I don't know enough about networking to know where to really look. So I'm hoping that someone can assist. It's a long read because I'm not sure how much information to provide at the start, so I hope you won't mind.

The problem is with a little technology by Logitech called "Flow" and peer discovery. Flow doesn't always find the computers on the network, or takes a very long time to establish a connection - when I reboot my computer, I have no way to force Flow to find the other computer on the network and re-establish the connection. It can take overnight after a reboot. It's maddening.

Some background:
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Logitech Flow allows you to automatically switch between computers by moving your mouse cursor to the edge of the screen. You can also copy and paste text, images, and files between your computers. If you have a supported Logitech keyboard, your keyboard can follow your mouse, giving you total control.

Logitech Flow uses the network to link multiple (up to three) computers and allow them to share a mouse and keyboard. To accomplish this, Flow uses a few different techniques depending on your network configuration:

For computers on the same subnet that can ping each other using UDP broadcasts, Flow uses a fixed UDP port (59867) to listen for and discover other peers.

For those computers that are behind routers or firewalls, Flow uses a Logitech cloud service to assist with peer discovery. This discovery technique uses TCP port 443 to communicate with the server and UDP port 59868 to listen for pings from peers.

Once peers discover each other, they use TCP port 59866 to establish a secure peer network to send control data.
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I have two machines that are on the same network and subnet of my home LAN. Win 7 PC, and a Win 10 PC. I have an Asus RT-AC3200 router, and a comcast residential gateway on the LAN. I know I have double NAT going on but have to do a lot of research to solve it, so "It's on the list".

Using resource monitor, I can view the discovery process and see that while it's listening to UDP and TCP ports, TCP Connections show it's using port 443 to communicate with their cloud service. I can see send and receive bytes, yet no receive bytes by the Win 7 or Win 10 machine that is listed in Network Activity. I assume then that it must not be using UDP broadcasting to communicate.

When communication is actually established, resource monitor shows that it's using TCP port 59866, and the Win 7 machine is receiving bytes.

So it establishes connection eventually, and appears to be via TCP 443 discovery instead of UDP port 59867 discovery.

Problem is, if I reboot the Win 10 machine, I can wait hours or overnight in some cases for communication to be re-established.

Where can I focus my attention to jump start, as it were, peer discovery? It shouldn't take this long, and I wondering if there's a config in my network setup that may be impeding the discovery process.

I'd like to prove that it's me or wonky peer discovery implementation.

Any thoughts?

 

[ColinTaylor]

Just a thought: try disabling the Windows Firewall on the devices in question.

 

[YrbkMgr]

Just a thought: try disabling the Windows Firewall on the devices in question.

Yeah, been through all of that. I have Norton Internet Security, I have Zone Alarm Free. Disabled them both. Win Firewall not active. Besides, would they be culprits if flow was working, it just took a long time for discovery?

I mean, it's active now and working flawlessly. But if I reboot.... I'll be in purgatory until it decides...

 

[L&LD]

Norton Internet (anything) and Zone Alarm (free or not) are not allowed on any networks that I work on... even disabled, they still manage to mangle the underlying os.

Sometimes, even uninstalling won't help. You'll need to do a full install (clean) of the os to get back to a good/known state.

When the so-called 'security' is this invasive; the 'solutions' become the problem themselves.

 

[YrbkMgr]

Norton Internet (anything) and Zone Alarm (free or not) are not allowed on any networks that I work on... even disabled, they still manage to mangle the underlying os.

Sometimes, even uninstalling won't help. You'll need to do a full install (clean) of the os to get back to a good/known state.

When the so-called 'security' is this invasive; the 'solutions' become the problem themselves.

Hey, I appreciate you taking the time to read the post and reply. I understand what you're saying, but unless I can confirm that the software firewalls are the most likely culprit for the discovery issue, I'm not inclined to remove them.

Someone suggested that the double NAT I have going on makes peer discovery difficult. Do you have any thoughts on that?

 

[L&LD]

Can you test the double nat issue easily? Simply connect all three devices to the same router and see if the issues are mitigated or continue.

With the complexity of networking, I don't see the benefits of bringing in third-party software like you have to bolster a network. Particularly when they can do more damage than good without drawing attention to themselves (as it seems to be so in your case too).

To test this theory, bring in three of your friends (that don't use Norton or Zone Alarm) with their devices and install your mouse software on their computers on your network. Do they have any issues? If not; the software is highly suspect. If they do, there are other things going on than what has been brought to light so far.

 

[ColinTaylor]

So it establishes connection eventually, and appears to be via TCP 443 discovery instead of UDP port 59867 discovery.

As you say, it sounds like it's trying to use the cloud discovery mechanism instead of the local method. Perhaps because it can connect to the cloud service it's assuming that that's OK but doesn't realise it won't work because of your double NAT.

I suggest two tests.

1. Unplug your internet connection and then reboot the devices in question. In theory it should realise that it can't connect to the cloud server and will be forced to use local discovery.

2. Put your Asus in the DMZ of your ISP router and test the devices again.

 

[YrbkMgr]

@L&LD and @ColinTaylor Thank you fellas. You've given me some direction. It'll be a couple days before I complete testing and will share what I find if it proves to be helpful to others.

@L&LD regarding:

Can you test the double nat issue easily? Simply connect all three devices to the same router and see if the issues are mitigated or continue.

I'm not quite sure what you mean. I am only concerned about two PC's, a Win 7 and Win 10. So when you say simply connect all THREE devices, I'm not sure if I'm missing something obvious, or if you've said 3 accidentally. I was thinking that you meant connect the two pc's to the same router, but got hung up on *three*. Then I thought about it... they ARE connected to the same router, to wit, my RT AC3200. Again, I'm out of my depth for connecting dots in networking, so if you might spell out what you mean or point me to a resource, I'd be grateful.

To test this theory, bring in three of your friends (that don't use Norton or Zone Alarm) with their devices and install your mouse software on their computers on your network. Do they have any issues? If not; the software is highly suspect. If they do, there are other things going on than what has been brought to light so far.

Well now that's a good example, and worthy of consideration. The thing that sticks in my craw about this, is that this is Logitech; it's supposed to work on consumer level PC's (not exclusively); find me a person running a home network without a firewall. This technology works between PC and Mac as well. So since I've scoured firewall settings and logs without a single hint that they're playing a role, I'm going to have to put it lower on the list of importance. I know you know more about this than me, but I'm not convinced it's not my network configuration.

To wit, you and ColinTaylor both point to the double NAT issue. I'm putting that high on the list of suspects. Plus, it's easier to troubleshoot than to figure out how to live without software firewalls and antivirus...

1. Unplug your internet connection and then reboot the devices in question. In theory it should realise that it can't connect to the cloud server and will be forced to use local discovery.

Does that mean unplug the cable from the WAN on the router?

 

[ColinTaylor]

Does that mean unplug the cable from the WAN on the router?

Yes, or the internet connection on your ISP router. Whatever method works for you so that the Asus has a functioning LAN but no access to the internet.