Re: N900 refusing to connect to 3g mobile internet
 

When you "cannot open page with browser" but some direct-IP-coded application like maybe some internet radio station works, the problem is your DNS.

Proof: try to "ping 8.8.8.8" or some other wellknown IP and it should work.

Solution: fix your DNS. I'd say it is useless to reboot your device or anything like that.

Re: N900 refusing to connect to 3g mobile internet
 

Ping did not change. Sometimes it starts to shows connection info and sometimes not. Changing the connection to automatic and choosing the mobile connection provider from the list fixes it. It just consumes the power and not nice to change it from the settings. There is probably some of those apps which could make it easy to switch it off and on.