Rebooting known Windows PC causes new "blocked device" alert from Fingbox

Mike_Duncan

My Home network, which is monitored by my Fingbox, consists of my main Windows 11 Laptop and a mixture of other devices interconnected with an eero mesh network.  Every time I reboot my Windows PC, Fingbox sends me an alert that it has blocked 2 new devices from accessing my local area network. The MAC addresses provided appear to be random, so I suspect something similar to what we have seen with iPhones when we haven't turned off Private Wi-Fi Address.

My Windows laptop is connected to a docking station with an Ethernet connection to the eero router. I have searched the Ethernet configuration parameters for a setting similar to Private Wi-Fi, but so far have not found anything.  It is an inconvenience to have to keep removing the new device entries in Fing to set the Fingbox status light back to normal.

Has anyone else seen this issue? I am running Windows 11 Home 21H2 with all updates applied.

Marc

Agreed I can't find anything to point to Windows supporting random Ethernet Mac addresses.  Does the laptop have WiFi and is the wifi adapter active?  If it does and is, could this be something that is contributing to your issue?

Mike_Duncan

I did some further checking on the WiFi capability on my Laptop.  This PC has the capability to turn on/off the WiFi adapter. I tried the following re-boots:

• Ethernet network connection/WiFi switched off - saw 2 new devices, with MAC addresses NOT assigned to a vendor, which are blocked by Fingbox. This is the original situation I reported.
  
• WiFi adapter on/Ethernet disconnected - did not see any new devices!!
• Ethernet connected AND WiFi adapter switched on - saw 2 new devices, which were blocked. MAC addresses not assigned to vendor.

So this situation has something to do with my Ethernet connectivity:

• It has just started happening and I haven't changed anything on the Ethernet connection. I am using an Adam Elements CASA Hub Pro docking station, which doesn't have any configurability.
  
• I am thinking about getting a cheap Ethernet USB-C dongle to rule out the docking station.
• The blocked MAC addresses are random and don't match anything in my equipment, because they are not vendor assigned.

In the process of removing the "phantom" devices, so Fingbox will stop flashing, I noticed that I have to wait a few minutes to delete them from the devices list, otherwise they just return.  Can you confirm that this would be the expected response from Fingbox?

I will update this post, when I have made any more discoveries.  Hopefully, someone else will have seen this issue and give us some perspective.

Mike_Duncan

With a different Ethernet adapter, I still get a new blocked device reported by Fingbox.

Anker USB-C/Ethernet dongle (ASIX AX88179) and only one new blocked MAC address is generated, whereas I was seeing 2 blocked MAC addresses with my Docking Station Ethernet interface.

So this strange behavior is not being generated by the Ethernet interfacing device, but rather by Windows ethernet support. Remember, we are not seeing the blocked MAC addresses when using WiFi.