I had problem with hotspot in Xiaomi Mi5s Plus after updating to MIUI10. I used ADB:
settings put global tether_dun_required 0
Unfortunately, after that mobile data and 4G network stopped working. Changing back this setting to "1" or "null" doesn't give any resoult.
2G and 3G network works (calling only, mobile data doesn't), I tried default settings, I tried restarting APN - no resoult. I got only notification, that system cannot install SIM Card. I already reinstalled my system - also no resoult.
//Small edit: I partly solved the problem by changing SIM port (my phone has dual-sim), but when I put SIM card to sim1 again - problem still exists. When I put card to sim2 slot it says that it uses "default settings" and it works as should. What can I do to reset settings of sim1?