- Edit Registry or create GPO:
- Create new DWORD value: AssumeUDPEncapsulationContextOnSendRule
- Modify DWORD value: 2
These changes will fix those pesky L2TP-NAT problem.
Troubleshooting IssuesMake sure clients use the latest edition of Windows 10. Early versions had quirks where clients simply would not connect via NAT-T.
NAT-T does not work with the following editions:
- version 10240
- version 1511 (i.e. November Update)
- version 1607 (i.e., Anniversary Update)
- version 1703 (i.e., Creators Update)
Some folks had to toggle the NAT-T registry value in order to connect (http://bit.ly/2r2CKnF). I assume this fix was for the November or Anniversary Update.
MTUDon't forget to adjust the Max Segment Size (MSS):