[LAU] Netjack2 and fast/normal/slow modes

Hello, I'm using Netjack2 between two machines, on a local network (ad-hoc) composed of this only two machines. I only want to send transport and MIDI data over the network. However I configure the slave mode, I receive message on the master telling me that the data are received too late: (slow mode) Warning : 'SCSTAGE' runs in slow network mode, but data received too late (3 cycle(s) offset) (normal mode) 'SCSTAGE' can't run in normal network mode, data received too late (6 cycle(s) offset) sometimes combined with this other message: NetMaster : overloaded, skipping receive from 'SCSTAGE' (only when using a MIDI output port on the slave) I use jackdmp svn turnk version and jackdmp 1.9.5 and 1.9.4 (this problems comes with all of these versions), in realtime mode on both machines, with a self compiled kernel on a Debian Squeeze system. Master is running jackdmp with FFADO 2.1 drivers for a Focusrite Saffire Pro 40 interface, with 64 samples per buffer on 2 or 3 buffers (2 is fine, 3 is safe!) at 48000Hz. RT priorities and permissions are OK. Hardware setup is quite the same on both machines: Proc: Intel Q6600 (Quad Core 2.4GHz) RAM: 8Gb on the master 4Gb on the slave Motherboard: Asus P5K-V, with gigabit network ethernet adapter: 01:00.0 Ethernet controller: Attansic Technology Corp. L1 Gigabit Ethernet Adapter (rev b0) I really don't understand why I get such warnings, as my setup is quite fine (I feel), considering audio, processors/ram, and network. Perhaps something to do with MTU, but I'm not really skilled about this! Any idea of what I should try? Thanks a lot.