Hi there,
sounds to me that it is an OS problem on the server site. In many UNIX
environments the scheduler will try to finish a job fast. If it then
realizes that won't happen it "nices" it, making it less important,giving
it less time slices. That continues gradually until the process gets
barely any CPU time at all. There are some servers out there that seem
to be busy enough for that to occur on a very regular basis. It is
nothing on your customers modem however. Also, you might wanna put a
traceroute on the server your client is trying to download from. At
times routers on the way might be down, causing timeout problems.