I know this thread was started over a year ago but I had this problem after signing up for unlimited data for a road trip I’m currently on. What fixed it for me was going to the “Wi-Fi hotspot” menu in the MyChevy / MyGMC app and turning on the “Enable Hotspot” switch. No call to onstar needed, and more importantly no more whining from my 15 yo daughter that the Tahoe’s Wi-Fi sucks.