I got my used n900 a few weeks ago, and mostly things are good, but I have a couple of problems.

How do I set up basic network filesharing with my other computers on my home wifi network? I can't figure out how to even SEE my other computers. No matter what terms I search for, I can only find info on media streaming and wifi hotspot stuff. I just want to send files back and forth, like my other computers do.

My only alternative is to use a cable, which I don't have, or remove the SD card every time, which is terribly inconvenient and feels risky.

Also, is there a pre-paid phone service that works for this model?