I got a new Intel Pro/1000 XT server adapter, a so-so switching hub (NetGear GS105) and I immediately upgraded my network. Since both the Intel adapter and the switch were jumbo frame compatible, I decided to try that feature out. Ran the following commands on the server (with the Intel adapter):

ip link set mtu 9000 dev lan

and after a small delay everything seemed to be OK.

Ran the same command on my workstation — an Asus K8V SE Deluxe motherboard with an onboard Marvell Gigabit adapter. The screen froze and after a few seconds the computer rebooted. That’s with a vanilla kernel. Gotta be more careful.