All the computers in this odd network problem run some sort of -current/i386..

work:
rtk -> hp   -> ex
fxp -> 3com -> ex
fxp -> hp   -> ex

doesn't work:
rtk -> 3com -> ex

The computers rtk,fxp,ex are labeled by their ethernet card drivers.
rtk/ukphy  fxp/inphy  ex/exphy

The switches are:
3com = 3com super stack 3 3300xm software 2.68
hp = HP2424M

"work" meant worked fine with autonegotiation. "doesn't work" means, I can
ping the 3com from rtk, but no further eg., cannot telnet into the 3com and
cannot ping ex. I also tried disabling autonegotation and trying each of
100 full, 100 half, 10 full, 10 half, setting both sides, and the fxp
autodetected the changes on the switch. (The same cables were used too..)

What else can I try? (Why did the rtk autodetect fine with the hp?)

Cheers,

Patrick