It's common that the ethernet cards in older macs don't play nice with newer network equipment. My SE's ethernet card doesn't like my gigabit router but works just fine with an 10mbps linksys switch in the middle.
The exact recommendation I have for you that I know has a 99% chance to work in your favor is a passive ethernet hub that is only 10mbps. if you have a switch or hub try it out.
Turning the port on the router down to 10mbps hasn't worked for me but it might work for you.
The problem is the cards don't understand the switching between 10/100/1000 but if there isn't switching involved then theoretically it works.
Also OpenTransport is the newer TCP/IP subsystem that replaced MacTCP . OT that was used from (I believe) 7.5 till 9.2.2 (some early OSX had it for compatibility).
The exact recommendation I have for you that I know has a 99% chance to work in your favor is a passive ethernet hub that is only 10mbps. if you have a switch or hub try it out.
Turning the port on the router down to 10mbps hasn't worked for me but it might work for you.
The problem is the cards don't understand the switching between 10/100/1000 but if there isn't switching involved then theoretically it works.
Also OpenTransport is the newer TCP/IP subsystem that replaced MacTCP . OT that was used from (I believe) 7.5 till 9.2.2 (some early OSX had it for compatibility).