I have a Slate AX that I use to create a VPNed Wi-Fi network at home separate from my regular Wi-Fi networks from another AP. The WAN port goes to my home network (Not LAN. I know if it was the LAN port it could be causing DHCP collisions but that's not the case). The Slate AX goes through some unmanaged switches to my home router. This solution has been working without issue for over a year and I've been happy with it.
However, last night while I was asleep, my home network went down. All devices couldn't connect to the internet nor even the router IP. I tried even setting static IPs on the devices but they still couldn't see the router or even each other.
While diagnosing, I hooked up my laptop to the router directly and unplugged the switch it was hooked up to. It worked. I put back the switch. It broke again. I then tried unplugging specific wires on the switch and found that disconnecting one of the wires makes everything else work. That wire goes to another switch which my Slate AX is on. So I go to that switch and do the same thing trying to unplug specific wires. I unplug the Slate AX and everything works in my home network. I plug it back in and everything breaks again.
So I narrowed it down to the Slate AX somehow poisoning my entire home network. How could this be happening? Even preventing devices hooked up to the other switch from talking to each other! Even when they are static IPs.
I hooked up a laptop to the Slate AX LAN to try accessing the web admin page, but DHCP is not working and also setting a static IP within the 192.168.8.1/24 subnet and trying to connect to the router admin page doesn't work. Also, the Wi-Fi network from it shows but could not be joined. It seems like it's in a bad state. I have not rebooted the Slate AX so that I can preserve the state in case there is anything I can do to figure out what's happening? I captured wireshark while hooking up my laptop directly to the Slate AX WAN in case that helps. It just looked like a bunch of MDNS and DHCP packets.