Our office connectivity is a bonded T1, 3 megabits in both directions, but
something has driven PPTP performance way down of late. In testing from my
cable modem at home, I can get a sustained rate of about 60 KB/sec inbound
to the office, but only 5 to 10 KB/sec outbound, and the outbound
connections often stall. Through NAT, circumventing the VPN, up and down
connection rates approach the full 3 Mb.
I'm testing with scp, whose internal throughput meter is corroborated
pretty closely by m0n0wall's traffic graph, at times of day when the
network is almost entirely unused. The office router is running m0n0wall
1.2 on PC hardware.
I haven't found much useful information in m0n0wall's logs, but I'd be
grateful for suggestions on where to look for a culprit. Some of our
offsite people are occasionally dependent on VNC, which is pretty
frustrating with the outbound bottleneck.