My N800 connects to my WLAN network but doesn't connect to the internet (icl. email, rss, etc.). My laptop does connect normally so I suppose the problem resides somewhere in the N800.
It works fine through bluetooth gprs though. Just WLAN is causing problems.
So: it does connect to WLAN 10 out of 10 times but it does not connect further to the internet 9 out of 10 times (1 out of 10 times it suddenly does, but I cannot reproduce why or when).
Problem started yesterday after I had installed the new Mozilla browser. (Please note: just changing the engine to Opera does not solve the problem, neither does re-booting).
Does anyone please have any idea of what I can do to solve this matter (except a re-flash)?
Thanks for all help.

What is the wireless router?? What's the cable/DSL modem? Any firewalls in between? At my house, even if you can get on the wireless, you can't go anywhere until the firewall is set to allow the new device.

If the device is unconnected and I manage to change engine to Opera before connection is established, than I have a fair chance to connrect to the internet. Otherwise no way.
So apparently the device now defaults to a connection through the Mozilla engine which does not work. Even disconnecting from Mozilla engine and reconnecting through Opera does not work. The only thing that works is a "clean" connection after re-boot through the Opera enginge.
Anyone, please, help???

Bugs #1636 or #1653 perhaps?

Please post a comment in against the appropriate bug in Bugzilla with details of your setup so that you can help Nokia to fix this problem in the next update.

No N800 bug, no Mozilla bug. Resetting the router did the trick (although I still don't understand why my laptop did not have any connection problems through the same router).
Thanks for your kind assistence.