Just purchased the new Nokia Lumia 928 and noticed that if Wifi is turned on, I can't enable Internet Sharing. I get the error message "Connection not shared -- Internet sharing isn't currently available". After that, if I try to browse, wifi no longer works even though I'm still connected. I have to turn Wifi off and back on to make it work again. Now, if I have Wifi off first then turn on Internet Sharing, it works just fine. I read online here - http://discussions.nokia.com/t5/Nokia-Lumia/Amber-update-Lumia-822-Two-Internet-Sharing-problems/td-... , which seems to indicate some update from Microsoft or Nokia causing this problem. Anyone else seeing this problem?
The article you linked to suggests you try a device reset to resolve any potential hiccups with the Amber update.
A workaround, that seems reasonable to me, is to just turn off wifi if you want to use the phone as a hotspot. Yes, I realize this used to happen automatically; but if the hotspot (internet sharing) works, then the only "bug" is auto disabling of wifi. To avoid the error, disable the wifi before enabling the hotspot.
I don't use my phone as a hotspot, so haven't seen the error.