I have got the same problem with my new Xperia 1. First time I tried using Hotspot got the same error message, when tried sliding the switch to the on position. The switch slides itself to the off position and the error message appears.
I have spent one week contacting my service provider, trying my SIM on other phones and contacting the phone seller. The phone seller just give me the generic instructions to switch hotspot on, even though i have emailed a shot of the error message, explaining the problem.
Simple: the problem is with the Xperia 1 phone. With my SIM in my old Xperia Z5 Premium I have Hotspot with no problem whatsoever, as I have had it in use for the last 3 years. I use the same SIM on my brabd new Xperia 1 and Hotspot just does NOT work. Is this a factory problem and hence I should return the Xperia 1 I have just purchased and get my money back?
