Global protect VPN resulting in Internet connection cutoff

[Breezy]

Hi everyone.

I have a x2 Slate Plus router(wireguard)(server in US and client on another continent) setup on personal laptop for work. When doing normal browsing my internet connection is fine.

However after connecting to work global protect vpn i lose connectivity to the internet. Can anyone please assist with a solution to this problem?

[alzhao]

Try change mtu in your windows.

Can't connect to Windows L2TP VPN through GL-X3000 / Spitx AX

I have a GL-X3000 / Spitx AX I’ve purchased and I’m using to connect to Tmobile home internet. Everything is working great, except when try to connect to my office VPN. I’m not able to establish a connection from my Windows 10 PC (connected to the Spitx AX) to my office VPN, which uses a Cisco Meraki L2TP/IPsec VPN. I get the following error on my Windows 10 PC (VPN client) when trying to connect to my office VPN: “Cannot connect to VPN, The L2TP connection attempt failed because the security la…

[Breezy]

I have changed it twice today from 1500 to 1400 and 1280 for both ethernet adpaters.Still not receiving anything.

[alzhao]

Can you try even lower mtu?

[Breezy]

I lowered Ethernet 1(GLRouter) to 600 form 1280 and Ethernet 2(GlobalProtect) from 1280 to 900 and it started working smoothly.

Switched off everything,reconnected and the connectivity issues came back.

Then checked mtu again only to realize GlobalProtect has restored back to the original 1400mtu so lowered it back to 900 and connecton issues continued.

Now lowered everything to 550 and connection restored.
Not sure what’s happening but your suggestions are doing somtething thank you. Where do i go from here

[admon]

@Breezy

Now lowered everything to 550 and connection restored.
Not sure what’s happening but your suggestions are doing somtething thank you. Where do i go from here

MTU 550 is waaaaay to low, something is odd here. Normally you would need something like 1260 - but nothing under 1000.

[alzhao]

You should only need to lower the mtu of your computer’s Ethernet to GL router and make it persistent

[Breezy]

It’s quite odd. The no internet problems are persisting. I have tried changing MTU again and again with no luck at establishing a solid internet connection. It sometimes connects and i can browse then if i turn off the PC/Disconnect Global protect it stops working.

[Breezy]

Okay thank you I’ve figured and made it persistent, played around with a few MTU numbers for GL ethernet only but still getting the problems with internet connectivity once connected to Global Protect.

[admon]

Guess you can use something like this to get the best MTU:

Ping Test to determine Optimal MTU Size on Router

[Breezy]

I have done this and it’s not bringing up any optimal MTU. Instead its timing out.

[alzhao]

The global vpn application itself should detect optimal mtu. But it didn’t

[Ilian]

hi, I have the same problem I can not solve it, I could help me with some solution for this case. Thanks

[alen5193]

Hi there,

Can you provide your router model and firmware version number?

What options do you have enabled in your global VPN settings?

[Ilian]

Hello

[Ilian]

I only have the Block Non-VPN Traffic option configured in global VPN settings.

[Ilian]

the model is GL-BE3600 / Slate 7

[alen5193]

Hi,

I tested it for a day, turned on the device VPN, and enabled the "Block Non-VPN traffic" option.

There was no network disconnection for the time being, and the VPN was always in normal use.

If you turn off the VPN function, you also need to turn off the "Block Non-VPN traffic" option, otherwise the router will block normal Internet traffic (non-VPN traffic)

[Ilian]

HI
i have my own server configured in the router with opnvpn which i access through the wifi of the slate 7 router i connect to my work pc which has global protecto and zscaler installed. I can't browse and I can't connect to the tools at work either.

[alen5193]

You can use Trace Route to check where the network is broken and view the firewall and routing data in the main router.