I am having issues accessing an L2TP/IPSec VPN for my work through my Archer A7 (V5) router. The problem appears to be between windows computers and my router both via wifi and ethernet. I am able to access the VPN on mac devices through my Archer A7 and I am able to access the VPN on my Windows devices when I am on other internet connections (hotels, hotspots...). I am also able to access the VPN if I bypass the router by hardwiring straight into my modem. All of the ALG passthroughs are enabled on my router but I am unable to ping the server through my router.
The windows error I get is "The network connection between your computer and the VPN server could not be established because the remote server is not responding. This could be because one of the network devices (e.g. firewalls, NAT, routers, etc) between your computer and the remote server is not configured to allow VPN connections. Please contact your administrator or your service provider to determine which device may be causing the problem." This appears to be Windows error 809. I have tried about all of the common fixes I can find on the web.