Hi Daniel,
Thank you for your reaction.
The network card is an Intel I350. The driver info from ESXi is the following:
driver: igb
version: 3.4.7.3
There is also a driver update available: my.vmware.com/.../details
I already did the following setting:esxcfg-module -s "InterruptThrottleRate=8000,8000,8000" igb.
I think the server needs a reboot before this setting becomes active. When I still have no result after the reboot I am going to try the driver update for the intel card.
Very strange problem
Thanks
Allert