@LnxRocks 

Are you configuring the switch ports from inside its device management page directly when it has been adopted, or during the vlan wizard ?

I do have many SG and ES class switches and have never seen this, but i always configure my ports manually and not during the wizard.  My only though is if you are changing the native vlan on the switch uplink port without realising it?

  @GRL 

I'm not sure what you mean by the wiizard.  Here is the process I was using:

From factory reset state:

1) Enter the switch management page and configure DHCP and 802.1q vlan.

2) Once the switch receives an IP address from VLAN1, it appears in the controller as pending

3) Adopt the switch 

4) Switch adopts in and is shown as connected

5) Under Network Config -> Switch Ports make a change to any port and apply

In a few seconds, all devices connected to the switch willl lose connection.  The switch reverts to it's default IP of 192.168.0.1.  Going to the switch page it says the switch has been adopted.

It's possible I accidentally changed the Native VLAN (I ran so many tries they all blur together), but I thought I was being careful in later attempts.

Some other notes in case they are relevant:

• My router / dhcp is running OpenWRT and is not Omada
• The controller is directly connected to the ES210X-M2
• I bought an ES208G as a downstream switch.  Once I properly configured VLAN1 as a management VLAN it adopted into the controller and configured without issues (Even using DHCP option 138)

Thanks