wifi LAN issue

So now the question is how do I get rid of Bonjour Sleep Proxy or is that even possible or at all helpful? ! ?

Thanks for the Debookee link.

I wouldn't recommend that you try to get "rid" of the Bonjour Sleep Proxy. It is a open source component of zero configuration networking and is designed to assist in reducing power consumption of networking electronic devices.

Ref: About Wake on Demand and Bonjour Sleep Proxy - Apple Support

Looks like your network "mystery" has been solved.

You didn't mention it, but do you have a GoPro camera?

Every network device would have a unique MAC address. However, a MAC address can be spoofed. Are you saying that the app is stating that it found two devices on your local network with the same MAC address?

For this GoPro device in the LanScan app, what is listed under:

• Hostname
• Vendor
• mDNS Name

Also, is the Hostname listed greyed out?

Let's compare what is in the ARP cache on your Mac vs. what LanScan "sees." We will use the Network Utility tool built into macOS.

• Hold down the <option> key, and then, click on the Apple icon in the macOS menu bar.
• Click on System Information...
• From the System Information menu bar, click on Window > Network Utility.
• Click on the Netstat tab.
• Select the first option (if not already selected): Display routing table information, then click on the Netstat button.
• This may take a few minutes but eventually you will get the results from the Netstat command.

Please don't post the results, but just compare them versus what LanScan gave you. Do both devices with the same MAC address show up in the Netstat results?

When you have a moment or two, try something different, just to get a different look at things:

Open AirPort Utility on your Mac

Hold down the option key on your Mac while you double-click on the picture of the AirPort Extreme

A list of Wireless Clients will appear

Click on the small arrow next to each client for more information about the device

The Hardware Address is the MAC Address of the device

To be sure that you completely remove the LanScan app, I suggest that you download, install, and run an EtreCheck report. It will help identify any remaining components of this program ... if any exist. I don't expect that there will be any.

...but it may uncover potential other problems.

• You can download EtreCheck from here.
• Start EtreCheck from a normal user account. Optionally, you can run it from a user account with Administrator privileges.
• Select Options

  Verify that the two options: "Ignore expected failures in Apple tasks" and "Hide Apple tasks" are enabled." Note: They should be by default. You can skip this step the next time your run EtreCheck.

• Select a problem from the drop-down menu to enable the "Start EtreCheck" button. Optionally, you can add comments on what issues your Mac is experiencing, especially to aide others with similar Mac issues.
• Click on Start EtreCheck
• Allow the program to run to completion.
• When done, you should get a results report.
• Select the "Share Report" icon.

  Select Copy Report

• Paste the report to your reply post.

Please try the following:

• Run the Terminal app, located in /Applications/Utilities
• At the Terminal prompt, enter: arp -d * <return>
• At the Terminal prompt, enter: exit <return>
• Restart your Mac.
• After it returns to the Desktop, run Netstat again.
• What are the results this time?

Please provide a screen shot of the LanScan results. Before providing it, remove the MAC address column from view, by right-clicking anywhere in the LanScan title bar, and deselect MAC address and just let us know which are the two devices with the same MAC address.

That's correct, each network device should have a unique MAC address. Some may have more than one, but no other device should the same one(s).

Leave the Apple TV disconnected.

• Run the AirPort Utility, and then, select the AirPort Express base station.
• Hold down the <option> key, and then, click on Edit.
• On the Summary tab, it should list the MAC addresses for the Express. Do they match the ones you found with Netstat?
• Close the AirPort Utility

Now power-up the Apple TV.

• Again run the AirPort Utility and follow the same instructions as before.
• This time; however, note the Wireless Clients on the Summary tab. If your Apple TV is connected to the Express by wireless, it should appear here. It could appear as a name, IP address, or MAC address. If MAC address, does that address the same as the MAC address for the Express?

Ok, as I suspected, LanScan uses the following protocols to attempt to "discover" what devices are present on the local network:

• Address Resolution Protocol (ARP)

  The results would populate the MAC address & Vendor columns.

• Internet Control Message Protocol (ICMP) (specifically PING)

  The results would populate the IP address column.

• NetBIOS Name Service (NBNS)

  The results would populate the Hostname column.

• Multicast Domain Name System (MDNS)

  The results would populate the mDNS Name column.

• Domain Name Service (DNS)

  The results would populate the DNS Name column.

• Server Message Block (SMB)

  The results would populate the SMB Name and SMB Domain columns.

This information may not directly address why you are getting the results that you are, but it appears that one or more of the above is not either being sent properly or their results are being "corrupted" when displayed in the app.

That shouldn't be an issue. The list will rebuild as devices are added back to the ARP table on your Mac. Any time your Mac communicates with another device on the local network, that device's IP address and MAC address will be added to this table. I just wanted to be sure that you start with a "clean" table on your Mac.

Each networking device will have a similar table, including your routers. This may all be an overkill to address your original question, but I'm trying to rule out that the duplicate device was not entered into the ARP table by accident.

FWIW, I have LanScan Pro installed on my Mac mini and I cannot duplicate what you are seeing on my network. That doesn't mean it doesn't exist on yours.

... and did the results of Netstat match what you found with the LanScan app?