SLIP and I-Net PC ???

I wonder if anybody out there in "Informix Land" has success using a PC client application, such as PowerBuilder v3.0 or ViewPoint 1.0, to access an Online server through a SLIP (serial line interface protocol) line. Anyway, I encountered problems over a SLIP connection. The suite of connectivity software I am using include I-Net PC 5.01.WC1 and Ftp Software's PC/TCP 3.0. When PC/TCP is configured to interface to a 3Com Etherlink III 10BaseT adapter, everything works fine with both PowerBuilder and ViewPoint. On the other hand, when the same PC/TCP is reconfigured for SLIP with no other changes in the operating environment, both applications hang right after the password is given to I-Net. However, ILogin, the app bundled with I-Net; and common tcp/ip apps such as ping, telnet, and ftp work. In the server, sqlexecd's log file shows the same garbage when PowerBuilder 3.00 or ViewPoint 1.0 attempts a connection.