Disconnects with Windows 11 PC / 5G Router

[r4ndom81]

Hi,
i'm using Forticlient VPN  now since approx 1.5 years for work, without any problems.
Usually i connect over a DSL Line with a LAN-Cable connected to my Windows 10 PC.
Sometimes, due to provider problems, i also use a Mobile Data Card, which is operating in a 5G Router. It provides a Wifi net, which my W10 PC connects to and Forticlient also runs smoothly.

Recently, i got a second machine with Windows 11 installed. Over the "normal" house-Wifi everything also works but when i try to use the same 5G Router connection, which is still working on my Windows 10 machine, Forticlient connects and then always immediately disconnects. Tried also to connect the 5G Router with a cable, but same effect...

Maybe someone knows this kind of preoblems and may help. Would appreciate :)

Cheers

[r4ndom81]

So yes, over my phones wifi hotspot it also works.  I think we can now narrow it down to the incompativility between windows 11, the forticlient VPN and my (specific) 5 g router (ZTE USB MU5001 - which works on windows 10).

[Umirzak]

i have similar issue with my users, they randomly disconnecting from VPN,

we are using IP Sec VPN, just raised official support ticket, waiting for the solution. 

[r4ndom81]

So even the connection works with the Smartphone wifi hotspot (over my Pixel 8, as i statet before) it seems that wireing it over usb (teethering) also leads to the disconnects of forticlient.

[robR]

Hi r4ndom81,

An update from my experience for what it is worth.  Turns out it was my ISP (Telstra Australia).  I had to raise a complaint to their complaints department after their support team refused to discuss my problem - because I was having an issue with a VPN (they assuming like NORD etc) it was out of their cope to provide support.  I could not get them to engage in discussion.  I did not blame them or ask for resolution, but simply politely asked 2 questions - 1. Has Telstra undertaken any security updates in the time the service was affected and 2. Does their proprietary router system allow for the passthrough. I had similar issue as you describe... once the VPN connected, LAN was disconnected, then VPN dropped.  Oddly I could hotspot via an IOS device and it would work through the same internet connection.

Finally the Telstra complaints department undertook an investigation - not into my technical problem, but the way in which their support team had interacted with me (I had transcripts where they flat out refused to discuss my problem) it was discovered that indeed Telstra had pushed new policy settings into customer routers and there were a number of customers with affected services and the policy settings were being rolled back.  Within 24 hours I noticed that that my router had been remotely factory reset (all of my static IP's had been erased) the VPN suddenly just worked as before.  Anyhow - dont assume its your system or Fortinet.   

[r4ndom81]

Hey folks,
so update from my side: Downgraded the Mini PC to Win10 Pro now but the problem PERSIST!

Its soo strange: The 5G Router still works perfectly with my othe Win 10 PC but not on the said one, so @robR I think its also not a provider thing.

Dont know what i can do anymore unfortunately....

[AEK]

I wonder if it has something to do with IPv6.

Can you try this?

1. In case your router gives you an IPv4 address, then try force it to give you an IPv6 address only
2. And in case your router gives you an IPv6 address then try force it to give you an IPv4 address
3. Also try by disabling IPv6 on your Windows network interface (or WiFi) connected to the router

[r4ndom81]

Hey,
thanks @AEK. So what i did and whats the results are the following:

- Disabled IPv6 on the Ethernet Adapters Properties (unchecked in the "Networking-list")
--> Forticlient connects somehow: Bytes are send, the "Fortinet Virtual Ethernet Adapter" gets enabled, no bytes are recieved AND my Internet connection is completly gone on the PC.

- For the sake of completeness - with default settings (IPv6 and IPv4 enabled on the Ethernet Adapter): Forticlient connects, "Fortinet Virtual Ethernet Adapter" enables, Forticlient Window freezes for a short time and disconnects (jumps back to login Window), also the "Fortinet Virtual Ethernet Adapter" disables).

Did you ment that procedure? If so, its no solution unfortunately - In addition i dont know whats going on on the Router side: As said, its a mobile 5G Router [ZTE MU5001] with very little settings, so i cant see whats been provided in terms of IP6 or IP4, on the device. Or do i need to check this somewhere else? Im a long term windows user but no network specialist, so i dont know exactly if i did right or where exactly i can grab necesary informations.

As so often mentioned, i run the exact same setup on my other Win10 PC (nothing modified on the networking properties at all) and everything works perfectly over the 5G router.

I attached a screensot of whats additionally in my Network connection window: (Virtual)Ethernet is the one which connects shortly when using Forticlient, (Virtual)Ethernet 2 isnt doing anything at all and stays like this.....and i did enbaled disabled the IPv6 thing on my normal Ethernet Controller though, not on these virtual ones.

[r4ndom81]

This is what the status says on my Ethernet Controller.

Another additional information: The 5G Router is now connect via an Cat7 ethernetcable to the PC but it make no difference if connected over cable or Wifi.

[AEK]

- Disabled IPv6 on the Ethernet Adapters Properties (unchecked in the "Networking-list")
--> Forticlient connects somehow: Bytes are send, the "Fortinet Virtual Ethernet Adapter" gets enabled, no bytes are recieved AND my Internet connection is completly gone on the PC.

It seems connecting to the remote VPN server (even no traffic passes). You PC loses internet connection probably because all traffic is sent through the tunnel. You can confirm with command "route print".

Here you need the support of the FortiGate admin so he confirms you are connecting and so he troubleshoots the traffic issue.

[r4ndom81]

Hey,
so do you mean when then IPv6 is disabeled or on default connection? I mean, on my other PC it runs with IPv6 and IPv4 enabled (as said did absolutely nothing in terms of modifing network properties. It always works smoothly since more than 1.5 years), no problem - what is the differnce here, i try to find out?

And it also means, that i have to contact my companys IT dep. for doing anything on Fortigate? Im just an Enduser with no knowledge of Fortigate or else - just got the client to work remotly (statet that before). Sorry, if i ask possible "dump" questions :D