@BubbaBubba Check for any rogue devices, scan for malware, check for incorrect cables, and also check the wireless settings.

  @VictorWalker 

I have done as the commenters' suggested. I've removed much of the complexity from the problem. I've removed most of the devices from the configuration, removed all bonding, all Linux bridges and probably other removals.

This is my simplified configuration and current problem.

Linux Router / Omada Controller (brain) <----> switch-10 <----> switch-poe

Omada/Switches:

Linux Router:

root@brain ~

  # ip -d link show enp3s0f0 ; ip -d link show enp3s0f0.20

4: enp3s0f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000

    link/ether 98:b7:85:00:30:36 brd ff:ff:ff:ff:ff:ff promiscuity 0 minmtu 68 maxmtu 9710 addrgenmode eui64 numtxqueues 64 numrxqueues 64 gso_max_size 65536 gso_max_segs 65535 gro_max_size 65536 parentbus pci parentdev 0000:03:00.0 

6: enp3s0f0.20@enp3s0f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000

    link/ether 98:b7:85:00:30:36 brd ff:ff:ff:ff:ff:ff promiscuity 0 minmtu 0 maxmtu 65535 

    vlan protocol 802.1Q id 20 <REORDER_HDR> addrgenmode eui64 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 gro_max_size 65536

The interfaces are not on a Linux Bridge, so I don't think there's any routing happening between networks LAN and IOT.

However, Omada/switches have brain listed with a 192.168.1.1 (LAN) address, but on the Security network.

switch-10 port #8 has profile All.

I have been experiencing link down/up on brain when I make the configuration more complicated, but I wanted to resolve this before I started building back up the complexity.

  @BubbaBubba 

As you can see the switches/omada logs are showing 'brain' being moved back and forth from my IOT network and LAN network.