I have been using my Negus S 4g mostly to just tether, as it's old and partially fossilized already.
But a few days ago, it just stopped working. I have full 3G connection (never got 4g working, no big to me) when tethering is off, but when I activate it, I just get a grey network bar that doesn't turn blue.
It's been working like a champ for months, and just stopped all of a sudden.
I've reset my phone, formatted it, made sure tethering still on in Ting settings.