Stuggling with AWS VMx and connection back to meraki auto vpn sites

[LE1]

I've just deployed a VMx-L in AWS, dashboard is connected fine. I now need to configure it so the subnets inside AWS can see the subnets inside our network we publish using the autovpn. 

Do I just use a single subnet to a vpc in AWS and then do everything else in AWS or do I have to configure every subnet individually in both places? 

Is there any more documentation on this anywhere? All I can find is the how to deploy which worked fine.

Thanks in advance for any help on this,

Lee.

[alemabrahao]

You don’t need to configure every subnet individually in both places ,but you do need to advertise each AWS subnet you want reachable over AutoVPN in the Meraki dashboard.

vMX Setup Guide for Amazon Web Services (AWS) - Cisco Meraki Documentation

Jumpstart Your Meraki Auto-VPN Journey in the Multi-Cloud Environment

Solved: Re: vMX 100 multiple subnets - The Meraki Community

[LE1]

Apologies if I'm misunderstanding this, we have a bunch of subnets set up in AWS. If I need all of these connected using AutoVPN, I need to set them all up as networks on the VMX and Enable AutoVPN? Is that correct? 

L.

[alemabrahao]

You only need one Meraki network for the VMx.
You manually list each AWS subnet you want to advertise via AutoVPN.
AWS handles internal routing; Meraki handles VPN routing.

Take a look at the Additional VPC Configuration  session on the document.

[LE1]

We've sort of got this half working now, thanks for the assistance above. I put the VMX in concentrator mode and its come online, I added all the subnets in AWS and they are connected using autovpn across all our other meraki sites. My issue is with the AWS transit gateway. If I change the route to use the ENI for the subnets, it works. If I change it to use the transit gateway, it doesnt. Neither meraki or AWS have been able to help, they both just say, their side is correct. Has anyone managed to do this?