With IPV6 enabled on Windows 10 DNS resolution for remote network via VPN connection fail to resolve

03/26/2020 9 8629

DESCRIPTION:

• With IPV6  enabled on Windows 10  DNS resolution for  remote network via VPN connection fail to resolve. 
• We have reviewed name resolution working fine with IPV6 disabled. 
• IPV6 Discussion forum with respect to DNS Resolution over VPN.
• Network traffic  for remote resources were found to be traversing through Local LAN interface rather than Tunnel interface.

RESOLUTION:

• Post reviewing this behavior SonicWALL Engineering have identified the issue was related to metric value with respect to Interface.
• Post enabling of IPV6  metric Value precedence was given to Local Interface rather VPN Interface.
• These values could be manually changed in  "rasphone.pbk"    (IpInterfaceMetric=0 => IpInterfaceMetric=1 )
• SonicWALL Engineering have found a workaround to avoid manual modification of rasphone.pbk  through Configuration Management extension (CEM).

1. Log in to AMC.
2. Click on Maintenance in the left-hand navigation menu.
3. In the URL, append "?advanced=1", and hit return.
4. Click on Configure under the new section Configuration extensions.
5. Click New
6. For the Key field, put in EVPN_DISABLE_ROUTE_METRIC_CHANGE
7. For the Value field, put in 1.
8. Click OK.
9. Click Save,
10. Apply Changes (this will force an apply-all, making the changes take effect).

• CEM Could be used on standalone devices or could be pushed from CMS to all Managed devices.
• This issue is seen with recent compiled binaries and updates.
• Such changes pushed are applied during tunnel instance.  All values related to metric would be restored to default post Tunnel disconnection.

ISSUE ID:

191773