I've tried my best: ppp, wvdial, bluetooth dun and pan, usb-cable and still without success. Two different computers, both first with maverick and now natty. Desktop Gnome. Here examples:

1. USB-cable. Mobile broadbrand configured properly and says connected: no internet and disconnects. On network manager it says: mobile broadband used: never. This method has worked once or twice over 6 months ago on my other pc.
2. Bluetooth DUN: gnome-bluetooth does not have an option to dun, using blueman dial-up connects and shows network is visible on network manager, but it is not visible on network-manager.

Sharing wifi with Joikuspot (premium) seems to be hard for Ubuntu to connect to.
I've searched and followed all instructions I have find after investigating many wikis and posts. I have tried to configure tethering for hours and getting frustrated. Any solutions or is this a no-go?
I know this might be a bit more Ubuntu than Maemo -related so apologies.
Thanks.

Sharing connection to my debian worked out of the box with N900. If I remember correctly, I just picked PC-suite mode and picked the right connection from network manager.

Same here, but it worked for me only a couple of times and after that nothing.

i use "qt mobile hotspot" over usb with ubuntu without any problems. i'm not sure if it works that reliable over wlan too. i barely use it because of the heavy battery drain

This seems promising. Thanks for the tip.

I've done it to my Debian testing toshiba laptop out of the box by bluetooth.

I have tethered (PC-Suite mode) a few times before with xubuntu jackalope (9.04) without any issues. Though at times I have to reconnect to wireless broadband twice for it to work. This is using the networkmanager.

Could it happen to be issues with signal? have you also tried forcing to connect to wireless broadband by setting N900 in 3G mode? I know with autodisconnect it will turn off 3G mode when you're not connect to wireless broadband or you're idling beyond the set time frame. This option is not enabled by default but I have noticed sometimes switching from 2.5G to 3G takes sometime and it may case ICD (Internet Connection Daemon) to think that wireless broadband is not available cancelling the wireless broadband access.

If you force it to 3G mode with 2G/3G switcher program you maybe able to get internet access from there.

i've tested usb tethering in pc suite mode on two computers running linux mint; laptop with mint 11 and desktop with mint 10. it works on the desktop but not on the laptop. i don't know why. i think, but i'm not sure i remember correctly, that it used to work on the laptop with a different distro.

in any case, i eventually installed power kernel and mobile hotspot. it's a power drain, but it usually works.

used to work perfectly for me out of the box with 10.10, since 11.04, and now 11.10, mobile broadband via usb doesn't work and is a known bug with gnome-network-manager.

I now use mobilehotspot but it rapes the battery... I'm waiting for the bug to be fixed, shame as it was damn useful, especially with o2 and their unlimited (subject to fair use policy) data plan I'm on

Tuxsavyy: Yes 3G/2G issue has been ruled out.
HughF_UK: Another reason not to upgrade, good to know.

Qt Mobile Hotspot works both with cable and wireless. Excellent! I assume power consumption is not an issue when using usb.