diff -Naur xl2tpd-1.3.14-orig/examples/ppp-options.xl2tpd xl2tpd-1.3.14/examples/ppp-options.xl2tpd
--- xl2tpd-1.3.14-orig/examples/ppp-options.xl2tpd	2019-04-17 12:23:39.000000000 -0400
+++ xl2tpd-1.3.14/examples/ppp-options.xl2tpd	2019-09-24 20:47:35.056615746 -0400
@@ -1,9 +1,11 @@
 ipcp-accept-local
 ipcp-accept-remote
-ms-dns  192.168.1.1
-ms-dns  192.168.1.3
-ms-wins 192.168.1.2
-ms-wins 192.168.1.4
+ms-dns  8.8.8.8
+ms-dns  1.1.1.1
+# ms-dns  192.168.1.1
+# ms-dns  192.168.1.3
+# ms-wins 192.168.1.2
+# ms-wins 192.168.1.4
 noccp
 auth
 crtscts
@@ -15,3 +17,11 @@
 lock
 proxyarp
 connect-delay 5000
+# To allow authentication against a Windows domain EXAMPLE, and require the
+# user to be in a group "VPN Users". Requires the samba-winbind package
+# require-mschap-v2
+# plugin winbind.so
+# ntlm_auth-helper '/usr/bin/ntlm_auth --helper-protocol=ntlm-server-1 --require-membership-of="EXAMPLE\\VPN Users"' 
+# You need to join the domain on the server, for example using samba:
+# http://rootmanager.com/ubuntu-ipsec-l2tp-windows-domain-auth/setting-up-openswan-xl2tpd-with-native-windows-clients-lucid.html
+