Unifi UDMP Pro - L2TP Windows Client Connections Dropping

Networking & Firewalls
1

Have a UDM-Pro and am still waiting for the official Wireguard roll out arriving soon. Until then I have been using the LT2P server and on MAC I can connect remotely for hours but via a Windows 11 computer the connection drops after just 3-20 minutes. It’s happening with two Windows 11 computers and for the life of me I can’t figure it out.

Tried the regedit fix of AssumeUDPEncapsulationContextOnSendRule
Tried to delete and recreate the VPN connection
Tried to change IPSec Policy Agent to Automatic

Has worked flawlessly for over a year and now it just wont stay connected. Any ideas?

Thanks,

2

Have their been any recently installed update or changes from UniFi or Microsoft recently?

3

We’ve always done UniFi and Microsoft updates using the regular stable releases. Never early or release candidates. Never been an issue (till now?).

4

Ssh into you UDM and run

swanctl --log

Then connect to the VPN and see if there is anything in there that can tell us more.

5

Are they coming form the same IP? L2TP will drop if more than one connection is behind the same public IP.

6

Hey @LTS_Tom , now that the UDM’s support WireGuard and OpenVPN will my issue be resolved by upgrading to one of those services and abandoning L2TP? THANKS!

7

Yes, it was the same source IP

8

Yes, either one of those will solve the issue.