AnyConnect VPN extremely slow on Mac - fine on Windows

[msh3]

I have an MacBook Pro running macOS Big Sur 11.5.2. It's connected to my WiFi network and everything is running fine. However, when I'm connecting to my company's VPN via AnyConnect, webpage loading is slowing down extremely. I profiled the loading time, it takes about 20 times longer than without VPN.

When I'm using a windows laptop, connected to the same WiFi and the same VPN with the same credentials, it's even as fast as with VPN turned off.

I'm using a company profile where Tunnel-All is NOT active.

The Anyconnect version is the same on both laptops: 4.10.01075

I already uninstalled AnyConnect and reinstalled, doesn't help at all.

Any idea what's going on here? Any help aprreciated.

Thank you

[MHM Cisco World]

https://www.mseri.me/fixing-wifi-on-os-x-by-tweaking-the-mtu/

[msh3]

I tested the MTU value as described in the page with ping and got 1472 as the first working value. As you have to add 28, 1500 as MTU should be right, no? So unfortunately, this does not help.

[msh3 · Accepted solution]

Think I found the solution:

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvv66700

Always thought the Cisco Socket Filters are required for the VPN connection (because they are installed together with Cisco Anyconnect), but they are not. They are slowing down the complete connection, even if no VPN is used.

Really hope this is fixed in AnyConnect 4.10.02086. Cannot test yet, because my company has to update its complete VPN system first. Cost me so much time the last days.

As a workaround, I'm removing all three Cisco Socket Filter entries from Network settings. Works fine and fast afterwards with and without VPN connections. Problem: The filter entries reappear after every restart of the system and I have to delete them again.

EDIT: If you delete the Application "Cisco AnyConnect Socket Filter.app" from Applications, the filters do not appear anymore after an restart, and VPN is still working fine.

[msh3]

Not fixed in AnyConnect 4.10.02086 - same behaviour on my MacBook.

However, at least the workaround (uninstall Cisco AnyConnect Socket Filter.app) is still working.

[MHM Cisco World]

thanks for update us.