Just using my 10III on the road for the first time, and I’m running into the same problem 
. The phone itself has internet, but my laptop can’t load any pages. Trying to ping google on the laptop appears to resolve the IP but no responses are received. I get an error that “Destination net unreachable”.
On the phone ping to google seems to resolve to the same IP, but then it errors out with “permission denied (are you root?)”. Which is weird as I’m running the command as defaultuser.
–edit
Forgot to mention that tethering has been working fine with this sim for years on my previous phone.
I see a few other people reporting issues with the hotspot, but nothing that seems like a duplicate or a solution. Internet Sharing Not Sharing Internet comes close, but I haven’t yet been able to test if turning it on/off helps.