Thanx for all the info.
My guess so far is that the really slow connections is a duplex problem.
(Thnx for that hint Chris, I was tired at the moment I looked. Some cards are in
half duplex mode, when they shouldn't be. Is there ANY way in m0n0wall to tell
them to get of the cursed autonegotiation and set themselfves to full duplex ?).
The 54 Mbit connections might be due to the $#^$%& motherboards we've got.
I'm going to try a test setup with an other motherboard.
Thnx for the info again, and I'll keep you posted.