The basement switch should obviously be the root of your STP topology. The downstream ports from basement to the other switches should be configured as trunks and as a best practice you should enable root guard to prevent some other downstream switch from claiming root and changing your STP topology.   The ports on the downstream switches that connect to the basement switch should actually have loop guard however Meraki won't let you do that because those links will be the uplinks towards dashboard.  So no STP guard for uplink ports then.   STP doesn't really do anything to block DHCP specifically so there might be another issue going on in your network. ... View more