@modulusmath 

Hi there,

You can check out if the DHCP setting of the RE is Auto or smart DHCP.

By closing that one, it will be solved.

The RE need to monitor the front router to see if there's working DHCP server.

If there's not, the RE will turn on its own DHCP server for behind device to maintain the connection.

Thanks

@Geeker Hi and Thanks for the reply. The only DHCP setting on the RE220 is what I attached in the screen shot above. I don't see actually see any setting for 'smart dhcp' though. 

I do have a DHCP server running on the 'main router' - the AX50 - so based on my research I don't expect this to occur.

Thanks in advance for any further insights.