I have a V30 and since the Oreo update my hotspot will not push pass 90kbps. USB tether is having the same problem. I've used my hotspot intermittently since October for both my Xbox and Laptop no problem, usually having LTE speeds. I've used only 2GB of my 15GB so it's not throttled, even so it wouldn't be THAT much.
Wondering if any other members of the community are having hotspot issues? Not specifically with a V30 but Oreo in general. Only forum I came across was for a S8+ having hotspot configuration issues.