PLIP transmit timeouts -- any solutions?

I currently have a PLIP link to an old laptop running Linux (I tried to
install FreeBSD, but it freezes at the USB detection -- yes, I tried
disabling USB in device.hints, and yes, I've tried a 4.8 installation,
but the bootloader says that the kernel.gz is in an 'invalid format')
without an ethernet NIC. I've set up the routes, and I'm using PF to do
the NAT on my "external" (I'm running my network behind an OpenBSD
firewall running PF) interface. The machine can reach my internal
network and the Internet just fine. There's just one completely
reproducible problem: I receive "transmit timeout" errors when I try to
transmit any useful amount of data, say about 600 kB between 3000 kB.
The laptop's keyboard is slightly damaged, and the 'number pad' is part
of the actual keyboard, taking over keys such as 'o' and real numbers as
well, making a root login impossible, so I have to either move a
keyboard around or reboot the machine to fix the connection. I've tried
to transfer a new kernel tarball to the system in order to upgrade the
system, but alas, that's given a transmit timeout as well. The laptop is
currently set to use the ECP parallel port on IRQ 7, the same as the
FreeBSD desktop. Both the FreeBSD and Linux kernels are custom-built;
I'm running 5.1-R on the FreeBSD system and a 2.4.18 Linux kernel as is
on the Debian woody mini-install ISO, installed from the .deb on said
CD. I haven't checked to see whether that kernel is patched or not.

I've grepped through the mailing lists, but because PLIP is part of the
GENERIC kernel, and people like to post dmesg's and kernel configs to
the mailing lists, I received over 5200 results. Going through
groups.google.com and google.com itself are equally as dismal, though
obversely so: groups.google.com gives four results, none of which in
English, and google gives a couple of English results, from the old
Linux PLIP implementation. If someone can effectively translate Polish
or French, I'll be glad to read the groups.google.com posts. :)

Thanks for reading my rants, and thanks in advance for any assistance
offered in regard to this. 

Best regards,
Christopher Nehren