Forticlient blocks LAN connection

[robR]

Hello Peoples,

I am not a computer person, so type slowly so I can understand.

In other words - please treat me with respect as I may not understand terminology.

I have been through all my available IT resources and they have washed their hands with my problem which leaves me stuck.

Last week, for no apparent reason (perhaps windows update?), my VPN connection to my university for my course stopped working. Being an external student in a remote area this is a problem.  On my PC workstation, over the course of the last week, I have now completely reimaged my machine with a clean win10 64 install.  I have updated all drivers - everything from motherboard chipset, PCI and network drivers.  I am running windows defender in standard config but no other security such as nortons.

The symptoms are:

1. Send connection request

2. Receive MFA challenge

3. Forticlient says connecting after MFA challenge

4. Says connected, with bits received and correct IP address to host shown.

5. No bits received.

6. Connection drops after few seconds.

During this time my PC loses connection to the local network.  I cannot ping it from another device on network.

After researching forums it appears I have correct settings for DNS and can ping 8.8.8.8.

On the PC I cannot access anything on my LAN.

When I do a route print when "connected" I get:

0.0.0.0  0.0.0.0  my_gateway_ip  machine_LAN_ip

0.0.0.0  0.0.0.0  host_gateway_ip host_ip

I had checked that my router and ISP are not issue - I can successfully connect to VPN from an ipad over router and same ISP connection, so I figured it was my machine.

However I installed the latest forticlient on a different Win11 machine on the network and got the same dropout, meaning it is something to do with a windows connection to the router.

The dropout occurs for both ethernet and wireless connections to the router.

If there is anyone out there with suggestion on next steps I would be extremely grateful as I can't do my uni work without the connection.

[robR · Accepted solution]

Seems to have been an ISP issue.  My ISP (Telstra in Australia) refused to look at it because in their opinion it was either the vendor's problem or my IT dept problem, and making the VPN work was out of their scope.  Issue was that it did work until they changed their firewall policy behind their supplied router.  I agree that its not the ISP's problem, but my argument was that they needed to provide the advice regarding the firewall policy change.  Once I had gone down the path of lodging a complaint, my router was remotely updated with new firmware and the VPN now works.

[jintrah_FTNT]

Hi,

It is difficult to troubleshoot the system here, but try going to > Control panel> Internet options> Connections> Then 'remove' the connection named 'fortissl'. And check if it helps. Also, see the logs on FortiClient generated after simulating the issue, go to settings > Logging ->Export logs on Forticlient software which might be useful.

Best regards,

Jin

[robR]

Hi Jin,

Thankyou for taking the time to look at my problem.

I had a look at your suggestions.

When I look at the network connections, I see 2 Fortinet ethernets

1. Fortinet Virtual Ethernet Adapter (NDIS6.30)

2. Fortinet SSL VPN Virtual Ethernet Adapter

I have tried have them both enabled and disabled, but ant see how to remove them, but figured they may not be doing anything anyway as I have removed ethernet cable.  

I had a look at logs and there are no errors - everything says "OK".

This is really frustrating given it has just worked for years until this week.

I have even downgraded from win11 to win10 to test that scenario. 

My next step is to try a different router.

Thanks Again

[robR · Accepted solution]

Seems to have been an ISP issue.  My ISP (Telstra in Australia) refused to look at it because in their opinion it was either the vendor's problem or my IT dept problem, and making the VPN work was out of their scope.  Issue was that it did work until they changed their firewall policy behind their supplied router.  I agree that its not the ISP's problem, but my argument was that they needed to provide the advice regarding the firewall policy change.  Once I had gone down the path of lodging a complaint, my router was remotely updated with new firmware and the VPN now works.

[btan · Accepted solution]

Hi robR,

Thanks for updating your scenario. So the root cause is not related to Fortinet, it is something from ISP side. You may mark your reply as a solution and close this trend, thank you.