Problem:

While testing the Meraki Client VPN feature I noticed what I can only assume is a bug in Windows 10 (I am on 1803).

When selecting the Connect option from the WIFI/Network icon in the system tray, the connection would often hang in a “Connecting” state.

VPN connections hang in Connecting

Looking in the Meraki event log I would get the below;

Oct 22 10:31:48		Non-Meraki / Client VPN negotiation	msg: failed to begin ipsec sa negotiation.
Oct 22 10:31:48		Non-Meraki / Client VPN negotiation	msg: no configuration found for x.x.x.x.
Oct 22 10:31:24		Non-Meraki / Client VPN negotiation	msg: IPsec-SA established: ESP/Transport x.x.x.x[4500]->82.7.39.246[4500] spi=2174933844(0x81a2db54)
Oct 22 10:31:24		Non-Meraki / Client VPN negotiation	msg: IPsec-SA established: ESP/Transport x.x.x.x[4500]->82.7.39.246[4500] spi=190939951(0xb61832f)
Oct 22 10:31:24		Non-Meraki / Client VPN negotiation	msg: ISAKMP-SA established x.x.x.x[4500]-x.x.x.x[4500] spi:2fcc04ff9ff90469:779439138b14820c
Oct 22 10:31:24		Non-Meraki / Client VPN negotiation	msg: invalid DH group 19.
Oct 22 10:31:24		Non-Meraki / Client VPN negotiation	msg: invalid DH group 20.

Rebooting the client seemed to be a temporary workaround. But after a couple connections or the laptop going to sleep the issue would come back.

Workaround

The reason I say I assume it is a Windows 10 bug is because if I connect via Windows Settings > Network & Internet > VPN it works every time.

VPN connections hang in Connecting

I think what I will do if I can’t find a permanent fix is I will create some sort of wrapper application that just triggers “Windows Settings” functionality from a shortcut or system tray icon.

I will update this post as and when I find a permanent fix or a better workaround.