Switch DOS Protection - DHCP blocking

First off, I want to say Thank you to Sophos technical support for excellent work!  (Bryan L.)

This is why we are using Windows for DHCP rather than another solution:

In order for Windows DNS to update, for DHCP clients, the windows DHCP server must update DNS. If you DNS records get Stale or non-existent, you may see related errors appearing in Windows system / security logs.

Third party DHCP servers do not update DNS, so depending on your network it may be desirable for windows to handle DHCP.  (non-standard workarounds exist, (REG / Group Policies).

PROBLEM:  Switch was blocking DHCP requests passing through XGS relay from another network.  (SEE PIC)

Solution: Turn Off DOS Protection on Sophos switch