How to solve DNS resolve failed problem when connect to SSL VPN?

[pxiannie]

I'm able to connect to ping my server and access local system last week, but today I tried to connect it shows error DNS resolve failed. I did not make any changes and this error has been solved, why got this error again?  I cant ping my server in command prompt and access the local system now. My current version of FortiClient VPN is 7.2.3.0929, is it because of the updates?

Please help. Thanks!

FortiClient 
FortiGate 

[hbac]

@pxiannie,

Which server name are you trying to ping? Is it a local domain name? You are using public DNS servers. You won't be able to resolve internal domain names. 

Regards, 

[pxiannie]

Hi @hbac ,

Yes I'm trying to ping local domain name. I try to use FortiGuard DDNS also not able to ping. My SSL VPN Setting's DNS server are same as the Dynamically Obtained DNS Servers.

[hbac]

@pxiannie,

Are you able to ping public domain name such as google.com, fortinet.com, etc?

Regards, 

[pxiannie]

Hi @hbac ,

I can ping public domain. My destination set to local lan 192.168.1.0/24 and I can ping some of them like 192.168.1.1 and 192.168.1.2. But some reply from my remote ip address and show destination host unreachable, and also request timed out.

Regards,

[hbac]

@pxiannie, 

You are able to ping public domains which means your DNS is working. I think you cannot ping your local domain name because you are using public DNS servers? which local domain are you trying to ping exactly? 

Please note that ping might be blocked by Windows firewall. 

Regards, 

[pxiannie]

Hi @hbac ,

I used Dynamically Obtained DNS Servers as my DNS Server in SSL VPN Settings, is that internal DNS server? I would like to ping my server name, which also the ip address in the range of local lan destination address. I cant ping the server when connect to ssl vpn but can ping using local lan, is it blocked by Windows firewall?

Regards,

[hbac]

@pxiannie,

No, you cannot resolve internal domain names while using public DNS servers. It will not work. You need to use internal DNS server for SSLVPN settings. 

Regards, 

[pxiannie]

Hi @hbac ,

I ady set to internal DNS server but still have DNS resolve failed problem. Is there anything wrong with my ssl vpn network connection? 

This is my network connection details using local internet.


This is my network connection detail after connect to ssl vpn.


Regards,

[hbac]

@pxiannie,

You are using 8.8.8.8 which is a public DNS server. It will not resolve your internal domain name. You need to specify your internal DNS server under SSL VPN Settings. 

Regards, 

[pxiannie]

hi @hbac ,

I think my internal DNS server is set to 8.8.8.8 because I check the dns server of local ethernet it is 8.8.8.8 . If not this the internal DNS server can be found in fortigate ?


Regards,