G4 startup very slow when connected to ethernet.

[Shabbyroad Media]

I have a G4 running OS9.2
When I connect the machine to my network the startup takes perhaps
half-an-hour and 
once near reaching the standard desktop/finder performance (such as mouse
movement) crawls along.
When I disconnect from the router the problem disappears. No other PC or Mac
or wireless AP on the router have any problems.
Lately the machine has also been giving me the floppy-disc-question-mark
icon on startup and after a minute or two finds the startup drive.

Do these point to basic underlying problem or are there simple explanations
for each ? 

I've reset PRAM and rebuilt desktops.

The other hardware in the machine is a Digidesign TDM system (2 cards plus a
SCSI card) and a dual monitor Jeronimo J2000 Appian card.
The system has been running fine for the past 3 years.

Tips/hints/suggestions welcome.

Peter, Dublin, Ireland.