netcfg put "ne io=0x300" and "ne io=0x240" .... The second
one replaces the
first so the first ethernet card is not found. netcfg
should use "ne io=0x300,0x240".
netcfg never writes to /etc/conf.modules.
Perhaps you were using linuxconf?
I think that "netcfg" was a typo for "netconf" which is part of linuxconf.
I've since heard of this bug in linuxconf from other folks.
This should be fixed in linuxconf-1.16r10-1 (or later) that we will release
as an errata update after testing.