Forum Discussion
GlobalProtect VPN not working with T-Mobile
I have seen several posts about VPNs not working with T-Mobile Home Internet. What is T-Mobile's plan to address this? I contacted my corporate IT department and they said it's not their VPN. All wor...
Try lowering you MTU value on the VPN connection. I could connect with Global Connect and use network resources, but couldnt use internet or teams video while connected. Which really sucked as some of our stuff is web based. So I was constantly connecting and un-connecting to VPN depending on what info I needed, and where it was (web or office network) After running a ping test, I had to lower my MTU to around 1340 from the default of 1500. Once I did that, I stopped losing internet connection everytime I connected to VPN, and video in Teams worked as well. I stay connected to VPN for my work day with no issues now. I noticed that even outside of VPN, the router doesnt accept the default 1500 MTU size. I lowered it to around 1460 I believe. Not a lot, but it stopped the bottleneck at the router. I have the latest firmware for comparison.
for Windows, go to a command prompt and type this in
ping www.yahoo.com -f -l 1500
If it comes back saying fragmented, run it again dropping it to 1400. Keep dropping it until the ping successfully completes. Then move the value back up by 10 until it fragments again. Then back it down by 1 or 5 until it completes again. Once you find it, that is the optimum MTU value your router will successfully pass while running VPN. Anything larger, and you will get a packet bottleneck at the router, degrading some of your services like internet etc.
look up how to change the MTU value on the network interface once you find it. Make sure you run the test WHILE VPN is connected, as that interface is only running while connected to VPN.
