Google Wifi blocking Layer 2 traffic between LAN port and Wireless devices

[jps8]

Hello! I have an unusual problem that I haven't been able to find a solution to online and I'm hoping this community can help.

My home office network uses a Google WiFi as it's main Router and WAP. I have several devices on my network that need to talk to each other over a Layer 2 protocol that is specific to their operating system (QNX). It appears that the Google Wifi is blocking this traffic between devices connected to it wirelessly and the devices wired to it's LAN port. 

Here is my network setup:
Fiber ONT (ISP) >> Unmanaged Switch >> Google WiFi WAN port
Google WiFi Wireless Network >> Windows Laptop that is running a QNX Virtual Machine
Google Wifi LAN port >> Managed Switch >> Multiple Devices running QNX

My Windows laptop is able to talk to all of the devices via TCP, so I know that all of the devices are generally powered up, alive, on the network, etc. It's only the Layer 2 networking protocol between the VM and the other QNX devices that isn't working.

If I connect my Windows Laptop to the network via Wireless (as above), then the VM on my Windows laptop cannot connect via this Layer 2 protocol to the Wired QNX devices.

However, if I disable my laptop WiFi and connect my Windows Laptop directly to the Managed Switch via an Ethernet cable, the VM and the Wired QNX devices can communicate via the QNX Layer 2 protocol.

In other words:
This works:  Windows Laptop / QNX VM >> Managed Switch >> Other QNX Devices
This doesn't work: Windows Laptop / QNX VM >> Google WiFi Wireless >> Google WiFi LAN >> Managed Switch >> Other QNX Devices

This seems to rule out any VM settings as my issue, as well as ruling out the managed switch as my issue.

I've gone through all the settings on the Google WiFi and haven't found any that look like they're causing my issue.

All that leads to my questions: Does anyone know for sure that the Google WiFi blocks Layer 2 protocols between the wireless network and the LAN port. And if so, is there any way to disable/bypass it?

Thanks in advance!

[olavrb]

Could be your managed switch, unless you've already disabled STP and made sure BPDU forwarding is enabled:

• https://support.google.com/googlenest/answer/6274262?hl=en

It also sounds like you run double NAT, why else would you have an unmanaged switch between your modem and the main/master/first Nest Wifi unit? Double NAT is not recommended, a switch between modem and main Nest Wifi unit is not recommended either. Modem should be in bridge mode and its Wi-Fi should be disabled.

[jps8]

Thanks for getting back to me!
I suspected the managed switch at first as well, but I've ruled that out as my likely problem because when I connect to that switch directly via an Ethernet cable from the laptop, everything works as intended.

The reason for the Unmanaged switch between the ONT/Modem and the WiFi Router is because I have multiple WiFi routers sharing the ONT's internet connection (via that unmanaged switch). That has been working flawlessly.

[olavrb]

Loop protection/prevention might act different on wireless vs. wired. Nest Wifi has built in STP, so no other device in it's network should have it too.

Ok, sounds like double NAT. It might work, but for the best experience with Nest Wifi, drop double NAT and make sure any managed switch has disabled STP.