I have a Meraki case opened but wanted to post here as well. I have an MS250 stack of two switches running 11.31 code. The switch stack is configured with several vlans and vlan interfaces all setup to relay dhcp to offsite dhcp servers. i have routers and firewalls connected to each switch in the stack for full diversity. switch 2 is the master based on lowest mac address.
routing is a default route from the switch stack to the fw-lan side ip. fw-wan side has a default route to the routers. both firewalls and routers are active/passive HA
physical connectivity is:
fw1-lan to sw1 on L3 vlan 1, fw1-wan and rtr1-lan to sw1 on L2 vlan 1060
fw2-lan to sw2 on L3 vlan 1, fw2-wan and rtr2-lan to sw2 on L2 vlan 1060
clients requesting a dhcp address works fine via both firewalls and rtr2 connected to sw2
clients requesting a dhcp address does not work via both firewalls and rtr1 connected to sw1
process of elimination troubleshooting has revealed the following:
It sounds like you have a loop somewhere.
These firewalls. Do they have a single connection to the switches each, or two connections (I'm going to guess two connections ...).
2 connections each. one on the LAN side and one on the WAN side. the interfaces are routed, not switched, so there are no BPDU's, etc. STP is also enabled on the meraki ports connected to the firewalls
FWIW, Meraki support has confirmed it's an issue with the non-master switch role in the stack and indicated code version 12.28 should fix it but it broke everything on the non master switch on my MS250 stack. they're looking into that issue now in development
@bmarms 12.30 had some more fixes and now 14.5 is out, I'd try that at a quiet time (and roll back if it is an issue)
Failing that, can you not stack the switches, I always find that works better than warm spare (from Cisco IOS days when we used to do that)
shouldve updated this one. there's some bug in their code. the fix was to add another L3 vlan interface, confirm the switches said "up to date" in the dashboard, then i could remove the new interface. something to do with the route table on both switches in the stack weren't synced.