A quick fix is to run this command:
sudo brctl setageing br0 0
This causes the aging of the MAC address to time out immediately or in 0 seconds, which delete the entry frmo the FDB (Forwarding Database) and causes the error to go away. The default time is 300 seconds or 5 minutes.
You can also add it under your br0 definition like this in /etc/network/interfaces to make it permanent and automatic:
auto br........
NetworkManager is normally good for GUI users who may not be good with manually confguring devices, but if you are using things like bridging and bonding, it will often break things.
How To Disable NetworkManager
systemctl disable NetworkManager
Now that it's disabled you will need to stop NetworkManager. NetworkManager will still be running until you reboot next or manually stop it.
How To Stop NetworkManager
systemctl stop........
Bonding is an excellent way to get both increased redundancy and throughput. It is similar to the "Network Teaming" feature in Windows.
There are a few different modes but we will use mode 6, I think it's the best of both worlds, as it is not just a failover, but it provides round robin, so you will get redundancy and load balancing. So if you have a 1G single port, you will have a combined throughput of 4G at this point. Just bear in mind that the true thr........