I keep getting "Network connection error" and have not been able to connect to wifi ever since upgrading to diablo. and reinstalling the OS. so basically I haven't used my n810 for at least 3 months now.

what can I do? has anyone experience this?

No. But you can go to "connectivity"->connections

then delete old connections or duplicated connections and see if that helps.

One thing that helped me once when I was having connection problems was making sure that the time and date was correct. I don't know why this helped, but it did.