Solved!
Turns out I was missing the "Apple Ethernet CS" extension under 7.5.5 for whatever reason. I copied it over from the 8.1 installation and everything seems to be working now.
Thanks to both of you who tried to help!
Sorry, I should have been more specific.
Connecting to my home network so I can FTP files from my NAS with Fetch.
Under 8.1, its as simple as setting the connection type to Ethernet using DHCP in the TCP/IP control panel.
Doing the same under 7.5.5 does not work. It doesn't appear that it is...
I have a Performa 575 with a comm slot ethernet card.
Everything works under OS 8.1 without issue.
Under System 7.5 I can't get a connection though. I've updated to 7.5.5 and updated Open Transport to 1.1.2. Nothing.
Any thought would be appreciated.
Thanks.