UDP traffic over 3G modem cut after 2 minutes?

On Leopard 10.5.2, UDP traffic over the Vodafone 3G Modem is cut after 2-3 minutes.
I'm not sure what's to blame, symptoms are

  • ping showing a message I've never seen before



  • some-macbook-pro:~ u$ ping 192.168.1.1
    PING 192.168.1.1 (192.168.1.1): 56 data bytes
    ping: sendto: No buffer space available


  • and a message in the system.log


  • dlil_output: output error retval = 37



The solution that works in my case is to stop the Cisco VPN client:


sudo SystemStarter stop CiscoVPN


And this is the thread over at Apple Discussions that discusses the problem and possible solutions.