There are many blogs and forums detailing how to generally set up the L2TP VPN Client on both Ubuntu 16.04 and Fedora 26.
For Ubuntu 16.04, follow this excellent tutorial: Enabling L2TP Over IPsec On Ubuntu 16.04
For Fedora 26, you just have to install the following:
dnf install NetworkManager-strongswan \ NetworkManager-strongswan-gnome \ NetworkManager-l2tp-gnome \ NetworkManager-l2tp
My main confusion surrounded understanding the particular phase algorithms used by the Meraki vpn server, see: IKE Phase.
After reading countless forums and comments, I realized I needed to explicitly set the following phase algorithms.
Phase1 Algorithms: 3des-sha1-modp1024
Phase2 Algorithms: 3des-sha1
So in Network Manager L2TP, under “IPsec settings”, it should look like this:
So again, this will work with Meraki VPN. Other VPNs using L2TP may differ but this will be something you want to consider when setting up your vpn client.