I just bought the Samsung Galaxy S8 and surprisingly the darn hotspot does not work out of the box. I could get devices to connect to the S8’s hotspot, but they had no Internet. Bad, very bad.
I did not find good solutions anywhere on the Internet, and I read tons of resources and watched several videos–wasted hours of my life. Lost time at work, lost sleep, missed the gym. Thanks Saumsung!
I have been doing this 30+ years, so I know what I’m doing. I blame Samsung, this is outrageous. I almost returned the phone to T-Mobile. Anyway, here is the absurdly bizarre yet straightforward solution:
Go to Settings > Connections > Mobile Networks > Access Point Names
You might see “T-Mobile US LTE” and all the APN options are greyed out. Write down all those options on a sheet of paper, or whatever you need to do. Write them down exactly, especially the “APN protocol” and “APN roaming protocol”.
On the ACCESS POINT NAMES page you should see “ADD” at the top. Press that and name it something like “My APN” and then set everything you just copied from the old APN.
Another website said the default APN is “corrupted” but that sounds like BS to me. I think only one change is necessary. Change “default,supl,mms” to “default,supl,mms,dun”. (If the default APN wasn’t greyed out, you could probably edit this without making a new APN.)
NOTE: For T-Mobile, my “APN protocol” needed to be IPv6.
“Save” option is at the top, then make sure you tap the radio button to select your new APN. There is no need to restart the phone, it should just work. But you may want to stop and restart your hotspot if it’s already on.
If the new APN is not working, it will be painfully obvious because your Internet will stop working. If that happens, simply switch back to the default T-Mobile APN.