Low throughput between Meraki MX84's

[chorton]

We have 2 offices located about a mile apart. 

We just increased the speed from Cox to 500 mbps upload and download to match what the other building already has.

I get the full 500mbps at both buildings when I test speed.

If I transfer a file between buildings I can only get 23mbps?

We don't use the advanced security features but do use the VPN.  I was under the impression we should be able to get 300mbps vpn throughput.  

Am I missing something about the way this all works, or does it seem like something is not right?

Is my thinking completely wrong? 

[cmr]

Are you using the Auto-VPN / SD-WAN feature to connect the two sites?

Can you run a direct network test between machines at each site using something like LAN speed test?

[chorton]

This is test from pc in one building to pc in the other building.

[cmr]

You definitely should get better than that.  I have an MX65 at home and it AutoVPNs into an MX250 in the datacentre.  The connections at each end are 500/500 and I get more than 85Mbps real throughput in both directions on file transfers etc.

[chorton]

Yes both these buildings are using the autovpn.  I was doing the testing with iperf3.

[cmr]

You might need to lower the max frame size, perhaps there is something in between with a lower value that is causing larger packets to get fragmented (file transfers etc.)

[PhilipDAth]

Are you running the stable firmware release or better?  There were a bunch of recent bug fixes around fragmentation and AutoVPN.

[chorton]

both are on.

Current version: MX 18.105