I am using Telus modem Siemens se567. the strength is good, but I can feel something fishy.

1. When I use my N800, there are some websites which are very difficulty, or even impossible to browse. I brought it to a net-cafe, it has no problem there.
2. I have no problem to use my laptop (windows XP), but occasionally MSN reports there is drop out maybe because of poor wifi connection.

I followed the instructions to change wifi channels, but there is no effect. I test net speed with my laptop using netspeed.net, the download is 1250 and upload is 500. there is no big difference when I changed wifi channels.

i called Telus, yes, they said the network is fine.

any suggestions?
thanks in advance.

Modem as in dial-up? All I can say is that in the days when lots of us used modems, this sort of problem was very common, and that was in the days before there was an N800. Modem problems can be very difficult and deceptive, and the culprit is often line noise, which is affected by the path the signal takes over phone wires to get to you.

I think you should start with listing the web-sites. Also, have you checked same slow web-sites from your computer at home? If it's a network problem they should be very slow on a computer as well.