Connections to 2012R2 L2TP Server Fail From Windows Client But MAC OS X Works OK

Hello all,

I have a small Domain network and have set up RRAS on the server to accept L2TP connections using a pre shared key.

VPN works fine from Mac OS X & IOS Clients but always fails from Windows clients.

I have added the AssumeUDPEncapsulationContextOnSendRule registry value to


As in this Microsoft KB Link but the connection still fails

NPS is set up and working fine for VPN and Remote Desktop Gateway connections

Any advice is welcomed..


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Aaron TomoskyDirector of Solutions ConsultingCommented:
Are the windows clients joined to the domain? Do you have a public cert installed?
DeclaroAuthor Commented:
Hi Thanks for the reply

Clients are not joined to the domain and yes there is a trusted certificate (GoDaddy DV)

I have narrowed it down to a local problem on the site I'm trying to connect from as it works from other locations

Going to look in depth a their firewall and router etc.

will let you know when I have more info.

Aaron TomoskyDirector of Solutions ConsultingCommented:
Nice find on the local site problem! Probably something in their firewall not allowing passthrough IPSec.
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DeclaroAuthor Commented:
Found it was the local firewall and a problem with a NAT policy. Took the quick way and reset the firewall as not many rules. Working fine now.

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Aaron TomoskyDirector of Solutions ConsultingCommented:
Well done. Hope talking through it with me helped but you did the heavy lifting ;)
DeclaroAuthor Commented:
It worked
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