Haven't made any headway on this with Meraki support so I thought I'd ask here...
We recently installed some MS225-48LPs at a site, along with Meraki firewalls. Since we have a pair of firewalls in HA, we use an isolated VLAN on the MS225-48LP to 'split' the WAN drop to the two firewalls.
Our switch has an isolated vlan with just 3 access ports - one for the WAN handoff, and one for each WAN port on the Meraki firewalls. Pretty standard.
However, when we put one of our two WAN connections into the MS225-48LP and use this isolated 3 port setup, we get incredibly low throughput, like >1mbps. Pings go through and are consistent, but it's unuseably slow. If we replace that 3 port VLAN with a separate physical switch (a standard Cisco), it works fine, so we know the issue isn't with the firewalls themselves, or the ISP, or even duplexing (it's set to auto, which is correct and is working with the other switch). The site has two isps, both set up like this, and the other ISP works fine.
Has anyone seen this behavior before? Any tips welcome, thanks!!