Thank you for reporting this!From what I can tell, the cloud/dashboard is slowly being update to support the models we had been complaining about not having the DHCP Option 15. Hopefully it will take less than 2 years to get added I would love if th...

@CMR I tested it on two different networks - once was running CS 17.1.4 and the other CS 17.2.2. Seems like something changed on the Meraki Dashboard and not the firmware. Can't find any announcement about it.

FYI - It appears that this is no longer an issue. The note has been removed from the docs page and I was successful in assigning DHCP option 15 on a C9300-12Y-M switch.

I opened a case specifically asking for details on this issue with support and this is the response I received."...After reviewing it with the internal team, currently we do not support the custom DHCP options on the C9300 series switches and current...

@joey.debra is correct. You need to consider the packer per second load on the firewall. I've had to move a customer that was using an MX250 for all the L3 SVI and DHCP to their MS410-32 because of CPU overload. Firewalls don't operate as inter-vlan ...