Three things:

1) Are you running the most recent firmware update on your N770? If not, upgrade it now. Search in here and over at nokia's site for the latest firmware. If I were you I would search around for "2007HE", the 2007 Hacker Edition firmware for the N770.

2) Posting here isn't going to help you if it's a real bug. https://bugs.maemo.org/

3) Considering Nokia isn't really working on the N770 all that much anymore, if it is a real bug then I wouldn't expect a fix any time soon.

Now that all that is out of the way, I'm thinking it's a problem with your wi-fi router setup and not the IT. I've seen it before where sometimes the SSID of the router has to be set to broadcast or WPA2 "dumbed down" to just WPA, or sometimes the router is in b/g mixed-mode and for some odd reason THAT is causing the problem and it needs to be set to G-only. It can also be a problem if your router is using a wi-fi channel/freq that is subject to heavy interference in the area you're in. An engineering friend of mine once built a handheld 2.4Ghz wi-fi jammer as an experiment and would routinely walk around the local wi-fi-enabled park dropping people off the net within a 60 foot radius around him just for sick, twisted kicks.
Or your router is setup for MAC-address filtering or something like that. Many, many things to look at and since we don't see where you've stated that any other wi-fi devices work flawlessly or what the router's settings are, we can't really help you.