Cisco Meraki client VPNs (multiple clients behind same NAT IP)

Hi,

We have a Cisco Meraki MX84 in our head office and, since we cleared out in March, some users have been having issues making a VPN connection.

We tracked it down to homes where we have multiple employees and investigation by our support partner has indicated that it's related to the L2PT protocol and a known issues when operating multiple clients behind the same NATted public IP address.

Meraki only supports L2TP for client connections.

Where things get odd is that it's not consistent. Sometimes both clients can connect, when it's not playing nicely it's first come, first connected. This can then sort itself out later on or decide not to work for the entire day.

Reboots of routers and client computers sometimes works and sometimes doesn't. Resetting windows networking sometimes resolves the issue, sometimes not.

Routers/ISPs are a mix of vendors.

Has anyone come across this or has any suggestions as to why it works a lot of the time I'd be grateful for your input!

We're actually looking at adding a separate VPN using an Unifi XG but this will require an additional switch, the XG and additional public IPs from our ISP. Not the end of the world but expense my budget would rather put elsewhere!