i38HG ethernet speed

Anybody know what the i38HG wired ethernet speed is?  

I have a WRT54G (old but very functional) bridged into the modem and I want to replace it with a newer gigabit router but only if the i38HG won't slow the higher speed router back down to 100Mbps.  I suppose I could go back to placing the router behind the modem if I had to.  I have a NAS connected to one of the modem ports and my Linux machine to another, both with gigabit ethernet,  and transfers are clearly being limited to under 100Mbps.

Info appreciated.